More like https://www.mangago.me/read-manga/aisaretagari_no_gemini/ ? Where twins r in love with the same person but it just becomes polyam? NO INCEST THOUGH.
https://www.mangago.me/read-manga/ai_o_ataeru_kemonotachi/
This is one yaoi polyamory threeway relationship
Imagine the hair moves and we see stitches bro istg