If I put a 6.5 rms 100 watts and a 3.5 at 45 watts on the same channel would the wattage add together or would I over power the the 3.5 trying to power the 6.5. The 3.5 are for location. And they are both 4 ohm loads.

This is probably not a very good idea.

If wired in parallel the load will be 2ohm. Both speakers will see the same power......dependant on install and whether or not your amp is 2ohm stable.......could be a good or bad idea......you will not be able to cross the bass out of the 3.5 without an external crossover of some kind.......