I translated this as 'gaeth fy chwaer i ei thalu' , i.e. I added 'i' after 'fy chwaer' but this was marked as wrong. I thought both forms, with or without the following 'i' were acceptable.
Yes it should be accepted , but I will say that I personally wouldn't put the "i" in here since it makes the sentence a bit awkward to say.
OK, thanks - very helpful!
"My sister got paid" - "Gaeth fy chwaer ei thalu". Is it possible to say "Gaeth fy chwaer i ei thalu hi" or is this kind of heaping up of pronouns avoided?
Hmm, I would say that what you suggested isn't said. I'm not sure if it's wrong exactly but it's sound very clumsy and I've never come across it using the double barelled possessive.