I had (unknown to me 'til post diagnosis) a quite distant relative (grandmother’s sister) with MS. Nobody with any of the other conditions - that I know of. But then again, I do not have a very large family - no uncles or aunts, so no cousins, as both Mum and Dad were only children - so we probably don’t have a large enough sample to demonstrate what everyone would have got if the ailments were distributed according to the stats (that might be a very good thing!)
I don’t think the shared genetics mean someone else in the family WILL have MS, or one of the other illnesses mentioned. It just increases their lifetime risk. I do know a girl with five sisters (haha, I say “girl”, but she’s my age - but I knew her from school, so she’s forever a “girl” in my eyes) - of the six of them, my schoolfriend has Type 1 diabetes, another sister MS, and a third has had Non-hodgkins lymphoma (currently in remission after successful treatment, although I do not know if they ever pronounce you “cured”).
I know one anecdote does not good science make, but out of six sisters, three having something the matter, and all of them in the suspiciously linked group, does make you think it’s more than just bad luck. Although in a way, that’s exactly what it is, of course, because the genes you get are down to luck.
I did have another very distant relative with Crohn’s - my mother’s cousin (this is the opposite side of the family to the known MS case, so I don’t know if I got a dollop of bad luck from both parents). My grandma (Mum’s mum) had been rather keen that she and her cousin might hit it off romantically - which they never did - but Mum was nevertheless quite fond of him, and devastated to find out decades later that he’d died really young, from the Crohn’s. She’d always imagined him to be still living, with a family somewhere - the same as she was.
Anyway, completely off-topic - especially my gran’s failed scheming to get my mum married-off to the cousin! But I don’t know if there’s any relevance as far as familial risks are concerned. Generally speaking, the closer the relationship, the higher the risk, because you have more genes in common. If Mum had married the cousin, I’d have had no risk of anything, because I wouldn’t be here!