They will be spread across the remaining stats, the real trick is manipulate the growth of the stats such that you only spend your max feed value to max it out.
Assumption P9 4* pedigree (max 500) - each grade 3 feed give 15 pts and you get 15 pts spread across 3 random skills at rank up.
The idea is to get your stat to 485, then use a feed to make it 500. If the stat is 490 and you use a feed, you waste 5 pts.
The scenario I am not sure the stat is at 495, and you rank up. Does the system have the potential to assign to that stat more than 1 time. Basically, are the stat increase rolls done before any are applied or sequentially.