"I have two sisters."
Translation:Tha dà phiuthar agam.
Dithis phiuthar is a lot nicer I have to say, you do hear and see dà phiuthar / dà bhràthair quite a lot nowadays but dithis phiuthar is more pleasant. We will likely remove and replace with the number system for counting people as soon as possible but due to the nature of the software this change cannot be made in isolation so it will need to be done as part of a wider change. Cheers! It's on our list though.
Yes, but not using them is universally (so far as I know) unacceptable. So dà phiuthar is actually wrong. According to what I was taught, what I have heard from native Gaelic speakers, all grammars and dictionaries I have ever read, and even the GME kids in the local primary. There are lots of other words you could use to teach numbers that aren't people.