Why would you come as a package?
Why wouldn't he be allowed to have relationships or events with his biological family that don't include you?
If that's his choice and they love you then fine, no problem.
But insisting that is what should happen because of some idea that you 'come as a package' when maybe not everyone in the extended sees it as that way is what most people on this thread who disagree are objecting to.
If you have DC and marry someone with DC you do so without the consent of the extended family, it's not an agreement that they have entered into that you now 'come as a package' anymore than someone who has an existing relationship with anyone that then marries should have to consider that they now 'come as a package' as a couple so can no longer have individual relationships or attend individual events.
And my Dad did what you're saying, with the pressure and control of my Step-Mum and insisted the blended family 'came as a package' .
It caused lots of trauma and resentment and now my step-Mum is dead my bio family are all loving being able to spend time with each other and individually, and rebuild our relationships. And to be able to verbalise how much damage my Step-Mum did.
I'd like to say i'm a better person but it seems i'm not as I have taken some pleasure in the fact i'm now the one helping my Dad get rid of all of her stuff and change their mirror-wills and our bio family has come together to enjoy each other.
It's not just me, her own DS hadn't spoken to her for years and didn't bother to attend her funeral.
It certainly wasn't a 'blended' funeral, none of my bio family except my Dad and one uncle attended and my Dad is one of 4, his Mum is still alive and I have 8 cousins.
She reaped what she sowed.