My partner has recently moved into my home. I have two DC and he has one. It's a 3 bedroom house and so when his DC is over for the weekend she has to share with my youngest daughter but there isn't really the space for them both in my daughters small bedroom. His daughter can't share with my older son.
We are considering converting part of my garage into a bedroom for his daughter when she stays over. My house is mortgaged and in my name only. How do you think this garage conversion should be funded? Should I pay as it's my house? Should he pay as I am doing it for his daughter or should we split the cost 50-50?