Dh has 18 yo with ex-partner, who lives with her dh and mum (in mums house).
Dh has a particular set of skills that are useful around a house and historically he has always helped out his ex with these things in her house, some are jobs that could be done by anyone and on other occasions they should be completed by someone like husband.
Lately though, requests to fix/repair things at exs’ house come through his dsc (which he has gone over and done), however latest one is helping out with xmas, which anyone could do, including her dh or his dc (18), would it be unreasonable to say no! Jog On 
...I get the impression my dh is exp goto fix-it guy!