Multigenerational household

I hope you are protected financially, if the partnership breaks up. I know it doesn't seem possible now, but these things happen.

Make sure that the three of you have a signed legal agreement about what will happen if there is a parting of the ways. There are many unseen problems and you wouldn't be the first person to end in poverty because of the absence of a proper legal agreement.

Always plan for the worst scenario and then enjoy the best.

Don’t give yourself a small portion of the house , give yourself room to breathe and move around, or else they are getting the big house and you will have a small part of it, you will need to get separate Utility bills, so separate meters etc.
What happens if you are too unwell/ old to provide childcare? Will you do all of the cleaning and meals too?

I hope it works out for you all, I hope that you have protected your new home( and your investment) so that if it all goes pear shaped you won’t lose out to family or ex family members.