Update to alkimia 8
Move to extras/ from bionic backports
Investigate MPIR thing (but it's not high priority I guess looking at the faff)
Compile kmymoney with new alkimia
Check if current kmymoney release tar can compile with new alkimia.
If so merge alkimia from Neon/unstable to Neon/release-lts and let that compile
Test. Snapshot. Party.
Essentialy mpir is not compatible with gmp as they use the same symbols. https://lists.debian.org/debian-science/2015/03/msg00021.html
Debian made the decision to not have it in archive. I can package it, but I do not know what else we may have that uses gmp. It could very well break things. Just letting you know :)
This does seem kind of scary. libgmp and mpir have the same symbols so can't be installed at the same time I think. libgmp has a load of very vital rdepends
apt-cache rdepends libgmp10
and can not be removed from the system. So if we are to use MPIR which i think is recommended by the alkimia guy then that would need worked out somehow. It may be worth contacting him directly (Ralf) to ask what he recommends.
Looks like you already compiled kmymoney with new alkimia :) will test and merge unless already done.