Back to the original question - Gemma and Rita are not formally related at all.
Shammydodger and jno are quite correct in that Ray is Gemma�s first cousin once removed � and she is his. (An easy way to remember the cousin rules is that first cousins share grandparents, second cousins share great-grandparents etc. �Removed� means the cousins are separated by generation).
Where they are not correct is to apply the �in-law� suffix. Although Rita is married to Gemma�s first cousin once removed, there is no formal title for this relationship. You cannot have �cousins-in-law� or �uncles/aunts-in-law�. The only formal in-laws you can have are brothers/sisters-in-law and mothers/fathers-in-law.
The most common misuse of the �in-law� title arises when referring to spouses of brothers/sisters-in-law. Many people think that the husband of their sister-in-law is their brother-in-law. Not so. Your brother-in-law can only be your wife�s brother, or your sister�s husband. Your brother-in-law�s wife is simply that, and not your sister-in-law.