Bit uncertain about fare classes for joker
I want to book shorthaul avios flights for some family members during the English school summer holidays 2024. Fairly flexible on destination as long as they can get to a warm/hot seaside without too difficult an onward journey. Getting flights much more important than class of travel.
I thought I could be clever and use GUFs but, even though flexible-ish on dates, it turns out I availability is patchy. Seeing mainly R and some D.
Two questions -
1. I have read in GGL guide that using a joker requires D availability but does it also work for R (which I think is still a discounted fare just not as discounted as I)?
2. If I want to try to use a joker for economy what fare class(es) should I look for? I see from post #14 above that B works. Does anything else?
Thank you.