I have a macro to draw rather complicated diagrams in tikz which makes use of pgfkeys in order to be as flexible as possible on arrows, labels and their styles. I allow all the commands of the library cd. What I would need is a parameter/option, such as
Rrightarrow of the ams package, that I can pass as pgfkey which could draw triple (or even quadruple) arrows, precisely like I can pass the parameters
The following topics Triple lines in tikz and Costum arrow shaft in tikz contain some beautiful code going in that direction, but I am not able to squeeze them into a tikz-cd arrow-style option. I think I understand the code of the (second answer of the) second link, where in order to provide a 3-arrow or a 4-arrow, two different arrows are overlapped. Since the arrows of my macro are fixed, I cannot use this solution. I think the code of the first link could be used to provide a satisfying solution but: I don't know a lot of tikz yet (I have always used tikzcd), in the comments there they seem to imply that adding a arrow tip to a triple line is hard. I tried to play a bit with the code, modifying what I think should be chanced, but I haven't managed to produce anything concrete.