Depends on the story I mostly like solo LI cause it easy to write it without being boring. Harem is harder to write if you put too much LI cause mostly happens is just become fuck fest and also some LI gets forgotten with no content or development. Sharing is a different kind goes with...
If you are just in for the incest then don't and if some fucking chance you fell in love with a family member probably a 1st degree cousin (rarely happens to brother and sister specially if your living together) think it very carefully if its worth it. Downside to it is you need not to procreate...
That is why harem or polygamy relationship rarely happens in real life cause of jealousy. In the game the 3 daughters at some points needs to share and not get jealous for it the harem would work. If at some point harem would not work and MC must choose one the other two daughter is not being...