s it disrespectful to the birthmother if we see her extended family without her knowledge or consent?

We adopted our daughter 7 years ago as an infant. The adoption was semi-open with regular updates sent to the birthmom through the agency. We gave the birthmom our email address, but we never heard from her directly or through our agency. Not long into the adoption the birthmom moved, leaving no forwarding address with the agency. Earlier this year I informed a person I know who knows the birthmom’s family that my daughter is related to them by birth. She gave me an update on the birthmom and offered to call her. I agreed and told this person to tell the birthmom that I had pictures saved for her if she wanted them. The phone call revealed that at this time the birthmom doesn’t want contact. About a week ago the mutual friend informed the birth aunt that she knew the family that had adopted her sister’s baby. She was responding to a FB post the aunt made about disowning her sister for something she had done. I received a friend request on FB from the aunt, and we began to correspond. The aunt and her daughter, are very interested in meeting us, and we have agreed to meet in the near future. My only concern is about the birthmom. She and her sister are close but are not seeing each other because of the recent altercation. I don’t know if she even knows that contact has been made between us. Should she know? Should I find out from the aunt if she knows? My daughter is eager to meet her birth cousin, so I want the visit to happen. Is it disrespectful to the birthmother if we see her extended family without her knowledge or consent?