Thank you everyone for your wonderful suggestions. I appreciate them so much!
Okay, I think the yellow gold ring is out as far as wearing it on a daily basis. I'll have it blessed, but I think I'll wear that for special occassions.
Having decided that, I'm forced with a new decision. Many of you suggested moving my e-ring to the right hand. I agree, that would be great, the problem is that the ring is engraved throughout all the way to the bottom of the shank, with diamonds going 3/4 the way around the ring. This makes re-sizing out of the question. It was sized for my left hand, and would not fit my right hand without further resizing.
Thus, if the e-ring stays on the left hand, I can either....
b.) wear a very simple engraved band with my ering on my left hand (although I worry it will hide all the diamonds on the side and rub against them causing damage?) such as this one: http://www.antiquereflections.com/detail.asp?id=2491
I agree with Lola and isus- if you can, go with both, to honour your mother-in-law's tradition and wear the yellow gold one on your right hand, then maybe have a white gold ring made to fit your e-ring for your left.