Complex sentence: This is most likely the mound that Zealia Bishop got the idea from and had in mind when she presented it to Lovecraft, even if it's possible she also got a little inspiration from the other one or added a detail from it, intentionally or unintentionally.
Split into simpler sentences: This is most likely the mound that Zealia Bishop got the idea from, and had in mind when she presented it to Lovecraft. It is, however, possible she also got a little inspiration from another mound, or added a detail from it, intentionally or unintentionally.