Can anyone help/advise?

I always assumed when people registered their partner as their assistant that they actively worked together all the time.

My partner has his own full time job but works at home a fair bit or can be at home not working a lot too. So my questions is can I register him as an assistant even though he's in other full time employment? What does he need to pass/do?

I would want him to watch the odd mindee when I popped out for under 30 mins to do school/nursery collections only, I dont need him to do anymore than that. Or if I say I had a sleeping baby I may want him to be at home whilst they slept. Is any of this allowed?

Thank you :-)