Names and relationships

I am an adoptive mom with 3 young kids in very open adoption relationships with all 6 birthfamilies. I am looking for some adoptee perspective regarding my son and youngest since I am making decisions on what I think would be best for him. The delima is this, his birthmom has alot of anger and resentment towards me for maintaining a relationship with the birthfather and his family even though this was discussed briefly before placement and I said I would never deny my kids either of their birthparents. Because of this relationship she has little to do with us and no longer chooses to see her birthson when we are in town (its a 5 hour drive and we do it 3-4 times a year to see 4 of the birthfamilies). She and her family have also decided to continue to call him by the name on his original birth certificate and they see that there is no harm in this. He is only 17 months old now but as he gets older I think it will become more of an issue. A little background. She parented for 11 days because the birthfather opposed the adoption at first, until he saw there was no way to make their relationship work. They both came and spent the weekend here togeather a few weeks after placement and everything seemed to go great - but she left not wanting us to talk to him or his family and calling our son by the name she gave him. Prior to placement, they all agreed to the first name we gave him and we let the birthmom choose his middle name - a family name. What I would like to know is how important do you feel a relationship is with both birthparents and how would you have felt growing up if your birthmother and her family called you by the name you had with them for 11 days (and what will my other kids think of this). I'm asking because the communication is starting up again with her family and I want to make sure I am picking the right battles for my sons sake (not for mine or the birthmoms sake) Thank you for your feedback.