Not your worry and if DH has nothing to do with SD23 and doesn’t want to reach out that’s his choice. As for Lupus and Fibromyalgia, a lot of times they go hand in hand.  I had a friend with Lupus who was then diagnosed with Fibromyalgia.  She smokes and drinks and abuses prescription drugs so she is not doing well.  She has lost all of her hair and it appears in photos that her liver is enlarged.    People with lupus can live full lives but they have to be careful and take very good care of themselves, I highly doubt your SD23 will do that. 

I'm not an expert, but I think lupus is something that can only be diagnosed in the absence of other conclusive tests. I'm not sure there is a conclusive diagnosis for lupus. I think it can be debilitating and often lead to unclear symptoms. 

I, too, have a BM (and an SS) who often claim to have illnesses they do not have. BM recently emailed DH to tell him how hard her life was because she thought she had cancer, but actually doesn't. SS told DH months ago that BM had cancer. SS has also claimed to have asthma, anxiety, and possibly cancer (he did not have cancer). SS has also regularly claimed to have "broken bones", only to be fine the next day. He once fell at a water park and was sure he had a broken rib...I think what he really had was the embarassment of falling in front of others. DH ignores all BM's emails about her supposed illnesses. He did reply about her sister's cancer...she sent a total of seven messages over the course of a couple of months about how her sister had "the worst kind" of breast cancer. She ultimately told DH she may need to have him take extra weekends to "help" her sister's family. DH's only reply, "Sorry to hear about your sister. I will accommodate extra weekends when I can." 

I view BM's messages about her health to be fishing for DH to still "care" about her. He doesn't...years of abuse and parental alienation will do that to a person. 

Lupus is a real thing.. and it can be diagnosed and treated.. but people who suffer can have a range of symptoms and impacts.. it can attack organs.. including the skin.. I had a horse trainer friend who had lupus.. and she had to take meds and had issues with the sun and had good spells.. and not so good spells.

I remember when Fibromyalgia came out years ago.. my Ex mil swore she had it.. aches in her arms.. etc.. she chased diagnosis with Drs.. went to holistic healer types.. also.. got a lot of pills from them that turned out to be basically amphetamine like impact..

You know what she had? heart disease.. and she died of THAT .. the pain?  yeah.. the heart attack pains.. but she was convinced she had fibro so got her doctors going down that road.. and they didn't pay much attention to her heart issues.. (and women often have their heart diagnosis overlooked).

Fibro was also often thought of as almost a "in your head" kind of thing too.. or something people would claim to get sympathy.. get out of doing things.. 

IDK.. I think there is more general consensus there is more to it than that.. but I didn't know if there was any test for it now.

My brother came up with the above when his MIL was all trying to get away from her DH of decades without divorcing him. She moved to NM to help with her Fig-my-imagia.  Her DH was still working and followed her as soon as he retired.

Once she figured out that she was not going to be able to keep his money and have nothing to do with him... suddely no more Fig-My-Imagia.  Even after they moved back to their originall home from NM, no more Fig-my-imagia.

I know that there are people with legitimate Fibromyalgia who suffer significantly from the condition.

My money is on FF having Fig-my-imagia.

along with other auto immune diseases/disorders. I had extreme joint pain, these random bumps on my joints of my fingers, elbows, etc. Had two of the bumps biopsied and was seen by a dermatologist and then a rheumatologist because they were pretty stumped about this sudden on set of symptoms. Turns out I had somehow during the holiday season of being out and about gotten sick with parvovirus which I had no idea humans could get apparently children get it and it is called fifth disease and for me resulted in viral arthritis.

I don't know anything about Fibromyalgia, but I do know that for Lupus there is a blood test they can do. The test I had was a CTD Test which looks at 10 different markers and based off the results of the 10 markers plus symptoms they can make an informed diagnosis about it. So for example on my test I was below the reference range (negative) on all 10 markers so it is a low likelihood of SLE.

From what I have learned when they thought I had it, it is more likely for a person to develop lupus if other autoimmune diseases/disorders are party of a family's medical history.

. I suggested, lightly, that he "might" want to reach out, but he prefers to let the dust settle. He doesnt know where shes living since Toxic Troll moved. 

I think he is right. If he reaches out she may take it as a sign that she should ask for money or ask to move back in. 

I do realize that these are legitimate illnesses. But, I will admit that I am leery of some reasons for wanting testing. From what I recall of Toxic Troll's history, SD23's work history, and their habit of Dr visits, I would be wondering if this was an attemp to become eligible of SSI.

OSD here had an unknown living situation. I wanted DH to reach out too. His reaction was similar to your DH's. As the situation evolved, I realized he was absolutely right.

I know there are many people who legitimately have lupus but why is it often the flaky ones who develop this.  BM, after years of abusing prescription drugs, and after years of unknown symptoms, got lupus.  I didn't hear the details, just "I had to xyz for Mom, whine whine whine" from SD61 for ages.  Any day now, I expect SD61 to develop it, a perfect disease:  vague symptoms, imdefinite diagnostic tests.

I have an in-law with lupus; I also have in-laws who, for various reasons, have had mythical illnesses designed either to garner sympathy and attention, excuse them from the rigors of adulting, or both.

OSD complained of headaches and body aches, chasing a fybro diagnosis. While she didnt get one, she still leveraged it to avoid having to work much. When her H lost his job and she had to work, she would inevitably not get along with someone and soon have a "flare up" that prevented her from working. 

YSD is a pathological liar. At twenty, she first claimed to have breast cancer, then lupus. The relative who actually does have lupus found this interesting. YSD clearly had done some reading up on it, and even claimed to be seeing a rheumatologist. "Really, who?" YSD gave the name of an actual doctor, and it happened to be the same one treating relative. Oops, YSD. The relative was able to ask the receptionist if YSD was a patient there, and surprise! she wasn't. Its stuff like this that makes YSD such a scary person to be around. She constructs her lies, even doing homework to seem more credible. 

Some people just loves drama.   You have a whold  Family who loves DRAMA. This is not going to change.  
Part of disengaging is not to play into this. Not to play into T.T. Games. She has F.F. Playing   Being sick is better then working.  Just wants money from DH. To fund her life