hey

I only know of these two, they're both GL though:

https://www.mangago.zone/read-manga/luminous_blue/
https://www.mangago.zone/read-manga/goukaku_no_tame_no_yasashii_sankaku_kankei_nyuumon/ (age gap? don't remember)

Wish i knew of more but this is all i have, both BLs. I usually have to read books for better poly relationships since its not a popular theme in manhwa/manga/manhua

In the Castle: the Dragon's Erotic Education (Yaoi)
https://www.mangago.zone/read-manga/in_the_castle_the_dragon_s_erotic_education/

Who is a sweet cheater? (Yaoi)
https://www.mangago.zone/read-manga/who_is_a_sweet_cheater/

finished both and they're just straight up porn

omgg tyy

LMAO i'm dead at the fact that you've already read both. But no seriously! it's all smut when it comes to poly on here :(

it hardly even pass as poly

100% agreed, it's more like the Semes just settled on "sharing" but it's not a real relationship on all ends

sorry these kinda are also "sharing the uke" but they get along well so ╮(￣▽￣)╭
https://www.mangago.zone/read-manga/choco_strawberry_vanilla/
https://www.mangago.zone/read-manga/tachi_to_neko_docchi_ga_ii_no/
https://www.mangago.zone/read-manga/ai_o_ataeru_kemonotachi/
https://www.mangago.zone/read-manga/double_beastly_trouble/
https://www.mangago.zone/read-manga/aisaretagari_no_gemini/