You are not being over sensitive, it is a form of emotional blackmail .
I had similar with one of my children, there was a big crowd of relatives who all wanted to send cards, letter, photos and gifts to her. Quite literally a bin bag full. All full of " grandma will always love you, you will always be our baby, we will see you on your 16th birthday " .
My child had enough to deal with in her own feeling and loss. Without having to deal with the guilty feelings of a huge groups of adults. Not one of whom was interested in actually helping her birth mother out when she was struggling .
Or visiting her in foster care.
Or applying to be a kinship carer. Even though there were several who could have done so ( two siblings in their 20s and young grandparents . All had homes and jobs and partners )
No one wanted her. They just wanted to assuage their own guilt by sending piles of crappy toys and horrid clothes and emotional words in cards . It was therapy for them, nothing to do with the child's needs.
I completely accept that birth family members have very genuine feeling of guilt and loss when a child is placed for adoption. However I DONT agree that it's the responsibility of the child or the adopters to help with these feelings .
That's the job of social services - have a duty of support to birth family members.