So you want to mix your guitar and mic at the end of the chain in front of reverb? If you split Row A into Row B then the split becomes the new input and you lose input 2.
What you could do is flip it around, then mix (the opposite of split)
Put input 2 and 4 blocks on Row A put reverb at the end
Put your input 1 and 6 blocks on Row B
Mix Row B into Row A in front of the reverb (the M in the splitter)