I do not know how the phylogeny chart you have is, but it probably contains a series of apes, gorillas and Homo sapiens.
We know that gorilas don't walk upright, but Homo sapiens do. What you will probably have to do is situate the new species of ape somewhere in between gorilas and humans, in a way that the new species shares a common evolutive path with both.
Hope it helped,
BioTeacher101