Maxwellsmum I'm not sure that you can on-donate donated embryos either because there is a limit to the number of families donors can donate to, so its up to the donor how many and which families her eggs go to. If I had one left that was spare it would have to be destroyed or given to science.
I actually felt much less excited about the three DE embryos we had (believe it or not!) but I know that will change if I get UTD. I mean, I feel really excited that it would be much more likely to work but I don't have that level of er... bonding with them I guess (that sounds a bit weird, ha!)