It can be done, but you have to edit the routine which loads and carries out evolutions. I have looked at evolution data structure before and it basically is just is a list of every evolution in the game, which can be broken down into groups of five, one group per pokemon. There is no end or starter bytes for each group and therefore the game just counts in order to know which evolutions belong to each pokemon. So, you would have to edit the routine to make it count more evolutions per pokemon, or make a special case scenario for Eevee.
No, that won't work since YAPE has precautions against going against the game's limits. See my above post for a little bit more in depth on what need to be done.