If you mean, is there a way to take 2 or more games and combine them into one rom and assume it will all work out fine, then no, it wouldn't be easy at all. More work than it would be worth. If you were to code a series of games from scratch it would be a lot easier to combine them onto one cart / rom, but even that would take some skill.

MON has just told you it's virtually impossible to do that with commercial games... Forget about it, it's more trouble than it's worth.

NES addresses ROM data very differently from SNES, which makes it relatively easy for NES but very difficult for SNES.