REV0 of course we know
Freearc supports merged compression methods, the only thing you need to do is to create arc.ini file with compress/decompress commandline and copy archiver files into freearc directory.
Simplifying, freearc creates small parts, compresses them with first, second archiver a.s.o. and then add this part to main archive. Decompression proceeds in the opposite way.
But there is one problem: you can do this only via arc.exe, not freearc.exe, unarc.exe or unarc.dll
Yener90 used unarc.dll in his installer, so it's impossible to use merged compression