if i have 2 traps set and my opponent plays like..... jar of greed or something, i chain royal decree. to my own royal decree i then chain return from the different dimension. ok so here is my question. my monsters will be special summoned i know because of the way chains work. but at the endphase will my monsters be removed from play? i dont think so because now royal decree is face up on the field and it will prevent the last part of return from the different dimension's effect to resolve.. let me know.....

Yes...because, just like Jinzo, it will NOT negate any "lingering" effects at the end...

The ONLY way for the monster(s) to remain is to...

A.) Flip them f/d

B.) Remove them temporarily and put them back to "break" their connection

C.) Hope you bring back all monsters that are unaffected by the effects of Traps.

From what I can tell, your Monsters will still be subject to the rest of RfaDD since by the time Royal Decree is active, RfaDD has resolved fully. *Shrugs and waits for others to reply*

It's like how summoning Spell Canceller or activating Imperial Order after taking control of a monster with Change of Heart, Mind Control or Brain Control does not negate the part about returning them to their owner.