i just searched for it but i can't find it, it doesn't have a alpha/omega tag but i know the cover is baby blue and has two twins on it with blonde hair and a black haired omega
i found one similar but it wasn't the right one i read. and it has a different pairing with alpha/omega/omega.
ill continue to look for it (づ ̄ ³ ̄)づ
too bad~ that's one of my favorite 3some mangas! i feel like you're more into plotlines having to do with romance more than lust maybe? i do have a recommendation for yah. although this hasn't been translated yet it is one of the famous 3some mangas in japan. i have the link for the 1st volume (total of 3 vol).
http://13dl.net/%e6%9d%be%e6%9c%ac%e3%83%9f%e3%83%bc%e3%82%b3%e3%83%8f%e3%82%a6%e3%82%b9-%e3%83%9c%e3%83%bc%e3%82%a4%e3%82%ba%e3%83%a9%e3%83%96%ef%bc%81-%e7%ac%ac01%e5%b7%bb.html?__cf_chl_jschl_tk__=baa5eb5920c096867042a2d7825518f77de83aed-1583306419-0-AfTy8HRmZZIr_PiMbEp9vF5Ts3DSeOOMRBuVivTdqbwWC9jyYobG0lI0nkvLddqP2fg6YfGdJkLJUBqvrhSps3sIGsVM2aLaCKuf_jO5OAsgTYUy8e3zOiftCxUVIqd7-SbOZTjJZgjGfTd3aOHxHhmsDRUsyvErxyAWtVzhnsPPOBVGcCBVpnd3rjLKx4x4xnxfArdgYe6Ain8ci720iT6bvgcpyEiHIJ2zmNyShQnaQ0nxfSZ0eT-pJQRBNso7GIL3qlC8MbjOAQ9jCtofv0c5iOS2TjInUpsH96eibPh-EPD15w-sVj3b52MmgoKElXNhWm6nRQ1_ZTPylvWXiZsfepGffAWLraF3NsxrBvFCQEKYD0_2Ru8X97v3ef2PHA9EYwO-BUs8G9LXTRNfQEwR94ojlikElUG5Ke6myUrTPq1pA0C4s2jAWc9IUcExO860D8ee2mpsCCReazlZ6y2T3iTxT7uAZqF9EVqzhqB1YJbjks3Sls8oo6ol43rZ0dQBO287V9NZozFWkaQxgIzolV11qfwpIU3elopz8OWG
okay....
so we all know the basic fated pair system right? the pair will only be attracted to each other's pheromones & no one else unless one of them dies BUT after a few chapters in you kinda get the sense that the 2 semes may have hooked up a couple of times (yup they definitely did... doujinshi link below). so after they all confess their love for each other, yuuzen (uke) decides to choose both semes to bond with him. then they go to a hospital specialized in the bonding system & ask a doctor if it's possible for 3 people to be bonded. in other words, if 2 semes can bite 1 omega & form the fated bond. the doctor answers that it has never been done before so there may be side effects or there may not. BUT the doctor explains that it is rare for a fated pair to find each other, let alone 2 semes (who have been taking anti-pheromonal pills) to be living in the same environment reacting to the exact same omega's heat. he theorized that it may be that the 2 semes have interacted with each other by exchanging cells & bacteria multiples of times that the bodies happened to have also shared the fated pair dna (hint hint... they fucked, kissed, & kouetsu came in ginga a lot). yuuzen stares at them & they both look away MEANING yes the doctor's hypothesis was spot on. so there you have it~ ginga is a seke (⊙…⊙ ) it's definitely a new concept that this author created. but what leaves us puzzled is who was yuuzen's actual fated pair? we'll never know whose dna was shared between the semes (maybe kouetsu...?). oh & you can only find the 2 semes fucking in the doujinshi & not the original plotline. the link below will show you the rest but in clips. enjoy~ (▰˘◡˘▰)
https://www.pixiv.net/en/artworks/76545901
correction... the doujinshi is the prequel to the series so it's not a made up side story. it actually did happen & relates back to the 2 semes' relationship.
https://www.pixiv.net/en/artworks/76545901
Is it possible for an omega to have two paired alphas?? I don't want them to separate, besides it would be nice change to have that kind of relationship in omegaverse world