Why is my boyfriend not wanting to bring me and my son up to his baby mamma?

We been dating for 4 months but know each other for 1 year and half recently moved in with him and his daughter and his baby mama recently in the picture but he keeps telling he's gonna bring me up to his baby mama but everytime they video chat or talk on the phone he never brings me or my son up and we always have to hide everytime they video chat or even be on the phone but he told his mother that his baby mama knows about us but that's not the truth I don't know why he won't tell her about us...

Why is my boyfriend not wanting to bring me and my son up to his baby mamma?
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