I have 2 DSD (7,4) and 1 DS (6months) were struggling with what my name should be with the DSD. We have shared custody of them and its a complete 50/50 split. I have been in my step daughters lives since they were 9months and 3, their bio mum also has a partner who has been in their lives for the same amount of time. My fiancée split amicably and all four of us get on really well, we have a group chat to discuss everything children related. I get on well with bio mum and she buys me mothers day gifts from my DSD and we get her gifts too. I have always been introduced to them as my name and nothing else. About a year ago the oldest (7) done a homework piece on 'why she's special' and said its because she has 2 mummies and 2 daddies. After this she asked if she could call me mumma, I felt awkward at first and explained she already has a mummy and Im her step mummy, she was a bit upset but carried on reffering me to my name, however she kept asking if she could call me mumma. I took it as a compliment that she sees me as a motherly figure and spoke with my fiancée and said she could call me whatever she felt comfortable with but she should ask bio mums permission first as I don't want to feel like im replacing her in anyway. She came back and decided to call me mumma although she will use a mixture of both, sometimes my name sometimes mumma I respond to both and Im used to it now. We have since had a DS together and the 4 year old DSD is getting a bit confused. She doesnt understand why daddy refers to me as mummy when talking to DS but refers to me by name to DSD she often corrects him when hes talking to DS saying no daddy thats not mummy thats my name. Which hurts as I dont want my DS to ever call me by my name. We have explained to 4yo DSD that I am mummy to DS but im step mummy to DSD and that bio mums partner is step dad, since she has learnt about step parents she has asked if she can call me mumma + my name and the same with her step dad, dadda + his name so she can differentiate between biomum and step mum, I thought it was a good idea and will solve the DS issue. She went home to biomum and called me mumma+my name and biomum told her she wasnt allowed to because biomum doesnt like it. Since she has been back and told us she has said she still wants to call me mumma+my name but it has to be our little secret. I told her we should never keep secrets and maybe we should come up with a name that biomum is happy with. Have since asked 7yo DSD what biomum has said to her since she refers to me as mumma and she said that she calls me my name at biomums house but mumma when here. She said that biomum was upset that DSD didnt want to call her stepdad, dad and only wants to refer to him by his name and when shes prepared to call him dad when there then she can call me mum when here. Now I don't know how to approach the situation as I think the DSD should call the step parents whatever they're comfortable with. I also dont want to force them to call me 1 or the other and despite the good relationship I have with biomum I dont think its my place to bring this up?