Any talk of using frozen embryos for research should be stopped. How would you feel if someone came up to you and said “I want to help a soldier who just lost his arm, let me rip yours off so he/she can have one. After all, they deserve it, they matter more than you.” I am pretty sure no one would want to give up their arm, many people can function without one, and moreover, your arm has a high chance of being rejected by the other person’s immune system. Embryonic Stem Cell Research has gone NOWHERE! It is useless! Why? Because embryos keeping growing and growing. From the very beginning, certain cells are given certain purposes - to become the top/bottom of the body; to become heart muscles/leg muscles; skin/bone; each time one cell multiplies and splits, there is a unique purpose for those two new cells. Now take a growing embryo made of several cells which have unique purposes and inject it into an adult human. It is unknown whether this action will lead to rejection by the adult’s immune system and if it does not then the embryo will usually continue growing - becoming hair, bone, muscle, etc. Only it is trapped in an odd space now and often develops into a “tumor” on the adult. This is why Embryonic Stem Cells should not be used, are not meant to be used!
So what to do with all those “leftovers?” That is a good question and one which the Church Magisterium is praying about and carefully looking at. It may be a long time before there is a concrete answers, but right now the best thing is to keep the extra embryos frozen (expensive though it may be). And the second thing to do is educate married couples about Church teachings concerning IVF and educate them on acceptable ways to achieve fertility.
Immorality and ill-education come at an expensive price.