Expectations from relations

I will try to be brief
I came from a small family. 2 siblings, nether of whom have children so tend to have more in common, and still live reasonably close to each other. We are 200 miles away so only see them occasionally.
We have 3 children, with 5 Grandchildren between them. Due to my DH's work, while our children were growing up he was away from home all week, at home for most weekends.
Consequently the children and I became used to being fairly self sufficient. Since they have left home/married we have a good relationship with them, but equally we do not live in each others pockets, though the oldest 3 grandchildren have had us very involved. in their lives since they were born as they live nearby
We have also been Foster Carers for 34 years , yes, even when DH was working away from home, and this has obviously been a huge part of our and our children/grandchildren's lives.
So, a close but not claustrophobic family.

DH and I are now retiring from Fostering, though still have our 110th and last little one with us.
Because we do not need our 5 bedroom Victorian terrace house anymore we are selling and moving.
Our daughter with the youngest grandchildren are now, by chance, living in a town very near to where I grew up, and we have been able to afford the perfect house for us very close to them. Even my usually reserved sil has said how much he is looking forward to us being near, as they have never had any family living near them throughout their married life.
All good, we are all really looking forward to the move.

BUT, one of my 3 cousins lives in the same town. We keep in touch with all three, but this one reduced the contact to the obligatory Christmas card many years ago. He and his wife have lived in the same house for over 40 years---important point.
Their one son lives with his male partner over 100 miles away, and his relationship is not acknowledged by his parents.
Cousins wife has apparently caused a huge rift with my other 2 cousins, her husbands brothers, and is also is a lady who has a list of ailments as long as her arm and says that her husband is essentially her carer
Now she has discovered that we are moving to the same town, and on facebook is demanding that we make contact, and befriend them 'in their twilight years' as they are 'family'
She became rather passive aggressive when I tried to tell her that we lead our own lives, still have our FC with us---until she moves to her adopters, are used to being our own family unit, don't see my siblings very often because that is just the lives we lead. She is also offended that our daughter has not made contact, but that is purely because our daughter is busy with her 2 young children, being a Methodist Ministers wife and working---and has never met either of them

DH and I are really looking forward to spending more time with our youngest grandchildren, and with each other, especially when we do actually say goodbye to being Foster Carers.

AIBU that I do not want to be drawn into this woman's life, which I feel would be the thin edge of the wedge
One more point, I am allergic to cats and dogs, and they have both in their home.
I will suggest meeting in town, once we are settled and our Little One has left us

Sorry for the very long post.