Costs of own home, partner also self-employed. Is this possible for both?

Hello,

Currently, my partner claims 37% (actual surface area) of our housing costs as professional expenses and I was wondering if I

1) can also claim part of our housing costs as professional expenses and if there are any disadvantages if we decide to sell our house?

2) can use the same percentage, since we use the same surface area?

3) Or would it be more advantageous to claim 20% each instead of 37% (regardless from the 3% difference)?

Thanks in advance.