Property ownership - who receives the rent?

OK. In the normal course of things I know income follows ownership.

However, in the situation I have Mother moves into a local authority bungalow. House remains in her name but son and daughter spend £20K of their own money on renovations and then let out.

They come to me 6 months later and say the rental income is theirs. Mother had intended they have the property, otherwise they would not have spent money on it.

Is it feasible to get the property transfered now, but treat the rents as due to son and daughter from day one,on the basis that M was just holding the property for them?