#1 Seems you can overfill a project if somebody else has the project window open at the same time as you.

#2 After accidentally filling 12 branches into a project that only needs 10 branches I used stack-splitting to take out 2 branches. After I did that it would only fill in 2 branches at the time whenever I right-clicked the branches on my back to fill into a project.

#3 After using stack-splitting to put 4 branches into a project it would then again input 4 branches at the time - but if I pick up 4 branches from the ground, go to a project that has 8/10 branches, right-click to put the last 2 branches in, thus having 2 branches left on my back, I can now go open an empty project and right-click the 2 branches on my back and the 2 branches will turn into 4 inside the project.