You currently have
A>B>C
You may as well just link on the other ones
A>B>C>D>E
That way D can grant levels to C. Obviously D & E are going to run out of raf after all the others but when the A>B>C link runs out you will still be able to RAF a group of 3 C>D>E instead of just a group of 2 D>E
Basically there is no reason not to link C & D.
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