Let me translate:
you feel displaced op
and your own sister wouldnt do the same.
OP's sisters haven't bothered to create an independent, loving relationship with her nieces/nephews.
DH's sister has.
Yet you feel OP's sisters are the ones getting it right? Blimey.
i guess you will just have to grin and bear it -
The appalling sorrow that her children have another loving relative who actively seeks them out & loves hearing about their lives?
How is this to be borne?!!!
you are allowed to have uncomfortable feelings though despite the reaction of many posters here.
Of course OP is allowed to. Many posters her have given her the advice & pointers she asked for. Taken trouble to motivate her to examine what is driving her feelings of discomfort, so she can remedy them, & start celebrating the aunt's relationship with her DC.
whats the worst that could happen?
Well, a few PP might pop up to enable OP's inappropriate jealousy & possessiveness, instead of gently coaxing her to reframe it & get comfortable with additional love from extended family members.
There could be collusive sympathy, attempts to make OP wallow in her misery instead of snap out of it.
does she invite other relatives round?
You sound like a controlling boyfriend 😂
"Who else are you seeing? Is it that Mary? I don't like you seeing her, she's a tramp, she'll take you to nightclubs & you'll be unfaithful to me. John? No, he has a fast car & a holiday home in Ibiza, I don't like you seeing men who have more to offer than me. I don't want your mother coming round so much, she has too much influence on you. Who is this guy at work, is he coming on to you? Give me a list of all your friends & family, so I can vet them & ensure nobody I disapprove of gets access to you."