I tried the concubines for all in the previous Ck2 patches before Holy fury, it was very easy, but one way or another I found a solution to finally done it.
after downloading this mod and unrar it
1) make a copy of the following address Crusader Kings II Holy Fury\common and save it as a backup
2) replace the "common" file with the moded one
3) there's no shame enjoying play this mod so enjoy it as you can
- I've tested the mod with random religion/sects and found no problems if you found and reported to me and I hope I can fix it
- I made it available up to 99 concubines for every religion, if you suggest more or less don't hesitate to tell me so