Hey Chuffy,
Thanks for the update and great question. The short answer is yes. As long as we're taking vitamin D3 to prevent our CH, we also need to be taking the vitamin D3 cofactors and that includes magnesium.
The longer answer is magnesium as well as zinc are consumed in the enzymatic processes that hydroxylate vitamin D3, (add a Hydroxyl group [OH] to the vitamin D3 molecule's 25th position to form 25(OH)D3 and 1st position to form its genetically active metabolite 1,25(OH)2D3). The following chart illustrates the metabolic pathway vitamin D3 takes to arrive at it's goal of initiating genetic expression. The genes annotated in blue are responsible for expressing the enzymes needed along the way.
Multimedia File Viewing and Clickable Links are available for Registered Members only!! You need to

or

There's another enzyme, RNA polymerase that's essential in producing the messenger RNA (mRNA) during genetic expression that down-regulates the primary neuropeptides, CGRP, SP, VIP and PACAP, all of which play roles in the pathogenesis of CH. It's the down-regulation (reduction) of these neuropeptides by vitamin D3 that helps prevent our CH.
The following chart illustrates how a strand of mRNA is transcribed (copied) from the DNA helix then passed from the cell nucleus into the cytoplasm where it is taken up by ribosomes.
Ribosomes are sub cellular chemical factories that read the recipe or blueprint encoded in the mRNA then draw in amino acids from the cytoplasm to produce proteins. These proteins then act as autocrine or paracrine signalling agents to change cell functions to replicate, differentiate. up- or down-regulate genetic products or they signal apoptosis, programmed cell death.
Multimedia File Viewing and Clickable Links are available for Registered Members only!! You need to

or

In short, if this genetic expression doesn't take place due to a lack of magnesium and zinc, there's a greatly reduced CH preventative effect while taking vitamin D3.
Another very important example of genetic expression involves the COVID-19 vaccines. These vaccines are mRNA segments that have been isolated and reproduced in a laboratory. They contain the genetic code, recipe/blueprint for the glycoprotein spike from the SARS-CoV-2 virus. Ribosomes read this mRNA segment to produce the glycoprotein spike shown in the small circle, but not the entire SARS-CoV-2 virus illustrated in the following graphic.
Multimedia File Viewing and Clickable Links are available for Registered Members only!! You need to

or

This is where things get really interesting. In order for this mRNA vaccine to be effective in preventing COVID-19, our innate immune system, our first line of defense against invading antigens like virus, swings into action. This is where macrophages and neutrophils (special white blood cells that include natural killer cells) identify this glycoprotein spike as a non-self invading antigen or foe, then consume/eat the spike. This identification, friend or foe (IFF) capability requires the vitamin D3 metabolite 1,25(OH)2D3. Without vitamin D3 the natural killer cells cannot tell the difference between self and non-self so lack this essential IFF capability.
This process signals our adaptive immune system's B-Cells and T-Cells to swing into action. These two immune cells are capable of developing antigen-specific "memory" that confers immunological protection. B-Cells express antibodies uniquely targeted at a specific antigen, in this case the glycoprotein spike. They also alter their own DNA to retain the genetic code required to express these same antibodies at a later date if the glycoprotein spike presents again. Hence we have long term immunity that can last many years.
Once the antibodies produced by B-Cells start attaching to the glycoprotein spike, killer T-Cells are attracted to these antibodies and actually eat the glycoprotein spike and cells infected with this spike reducing them to harmless waste products that are eliminated from the cell. These processes also require the vitamin D3 metabolite, 1,25(OH)2D3.
There's a disturbing aspect of immune system activity that many emergency medicine physicians did not understand until the COVID-19 pandemic broke out. The initial battle waged against invading antigens by the innate immune system cells causes these cells to reproduce (replicate) rapidly and release cytokines that trigger inflammation. The natural killer cells and killer T-Cells continue to eat these virus with no problem.
However, the neutrophils and B-Cells die once they've eaten the virus and form pus which accumulates in the tissues lining the nasal passages and cells lining the lung's alveoli. Without vitamin D3, the immune system becomes dysregulated with uncontrolled immune cell replication and release of cytokines in what is called a "cytokine storm." The buildup of dead cells and pus inhibits the uptake of adequate oxygen in the lungs causing hypoxia. This is where COVID-19 patients require supplemental oxygen and if the cytokine storm continues, intubation. At that point, survival rates drop rapidly.
Bottom line, if you intend to get the COVID-19 vaccine, your immune system will need a lot of vitamin D3 to make this mRNA vaccine effective.
This begs the question, how much vitamin D3 is needed? Fortunately there have been hundreds of studies of COVID-19 and vitamin D3 looking at this problem. The following graphic, from one such peer reviewed study, gives us an obvious clue how much vitamin D3 we need to keep from dying from COVID-19. The answer is enough vitamin D3 to elevate 25(OH)D3 serum concentration > 40 ng/mL or a minimum of 5,000 IU/day vitamin D3 for at least three weeks.
Multimedia File Viewing and Clickable Links are available for Registered Members only!! You need to

or

The following chart illustrates the time course 25(OH)D3 serum concentration response to various doses of vitamin D3. As you can see, it takes three weeks at a vitamin D3 dose of 5,000 IU/day for serum 25(OH)D3 to reach 40 ng/mL and three to four months to reach 60 ng/mL. The 10,000 IU/day vitamin D3 we take to prevent CH is even better.
Multimedia File Viewing and Clickable Links are available for Registered Members only!! You need to

or

There are other peer reviewed studies that conclude the higher the 25(OH)D3 serum concentration above 40 ng/mL, the more favorable the outcome from COVID-19 and at a high enough serum concentration, COVID-19 will likely be asymptomatic when infected by the SARS-CoV-2 virus.
This is where CHers who have been taking the anti-inflammatory regimen with at least 10,000 IU/day vitamin D3 or 50,000 IU/week with the Bio-Tech D3-50 for more than a month or who started this regimen with the 12-Day accelerated vitamin D3 loading schedule, can breath a sigh of relief. Even if they can't obtain the COVID-19 mRNA vaccine any time soon, their 25(OH)D3 serum concentration has boosted their immune system functions to help prevent COVID-19 and the deadly cytokine storm. Their mean 25(OH)D3 serum concentration is illustrated in the following normal distribution chart from the online survey over 350 CHers have taken since December of 2011 at an average dose of 10,000 IU/day plus the cofactors.
Multimedia File Viewing and Clickable Links are available for Registered Members only!! You need to

or

The other thing people need to understand is even if they don't have CH and they've not been taking vitamin D3, their 25(OH)D3 serum concentration will likely fall under the following normal distribution chart of baseline 25(OH)D3 lab tests CHers took prior to starting the anti-inflammatory regimen.
Multimedia File Viewing and Clickable Links are available for Registered Members only!! You need to

or

As you can see, nearly 95% of these CHers had a 25(OH)D3 serum concentration less than 40 ng/mL and over 60% were less than 30 ng/mL. The 50% at and below 24 ng/mL would have been in deep kimchi had they been infected with the SARS-CoV-2 virus.
It doesn't take rocket science to realize everyone, including CHers, their families and friends all need to start taking at least 10,000 IU/day along with the rest of the vitamin D3 cofactors ASAP. Kids under 100 lbs (45 Kg) need to take between 50 to 100 IU of vitamin D3 per pound of body weight per day (110 to 220 IU of vitamin D3 per Kg of body weight per day) to attain a 25(OH)D3 serum concentration of 80 ng/mL (200 nmol/L).
As a side note, this regimen is so safe, I've had my entire family and many close friends taking it since 2011. That includes four grand babies my daughter and niece delivered flawlessly after very normal pregnancies. These grand babies were bathed in maternal vitamin D3 from conception through breastfeeding. As a result, they have T-Rex immune systems. They don't get sick.
My earlier post of 6 January provided the following vitamindwiki link.
Multimedia File Viewing and Clickable Links are available for Registered Members only!! You need to

or

It lists 34 trials, 4 trial results, 10 meta-analyses and reviews, 39 observations, 22 recommendations, 41 associations, 82 speculations and 34 videos about using vitamin D3 as an effective intervention for COVID-19. You be the judge.
So there you have it. The long answer.
Take care and please keep us posted.
V/R, Batch