
Dojin sister in-law is also male omega right? And why didn't he attend hyesung and dojin wedding? Is he opposed the union?

That's Dojin's sister. They probably were, but the wedding scene just didn't show them all. It was so short - like 1-2 panels? All of Dojin's sibling's were under Byul's charm, so for sure they'd be at the wedding.
Dojin's parent's were even starting to spoil Hyesung... omg, imagine you're in-laws giving you a credit card that you could spend to your heart's content!

No i mean dojin elder brother's wife (dojin 1st bro) the mother of dojin nephew
Here he is ------>
http://www.mangago.zone/read-manga/love_is_an_illusion/uu/love_is_an_illusion-chapter-44.1/3/
The one beside (left side of) dojin's mom and infont of dojun and dojin's dad, the one with brown hair on the left the shortest one with white shirt
YEAH DIE ALONE OF A HEART ATTACK AND HEART BROKE YOU SON OF A BITCH!!! Jiang wenxu you only valued zishu when he gone if he didn't have a cancer would you ever turn your back and treat him better as you promised him in the past? I think not you would still fuck around and ended being a colossal slut in this century you dick!! GO SUFFERING AND DIE ALONE FUCKER!!!!