I'm pretty sure it won't, but what's the issue ? Not long ago they were complete strangers and the only thing that makes a relationship between them incestuous is that their respective parent married each other.I just hope there isn't any real romance between the brothers... There is no incest tag so gotta pray it stays that way
If you have to ask that you didn't think it through. It's a one way ticket to turn the family into a completely dysfunctional family which will break the trust both parents have towards their children and even between each otherI'm pretty sure it won't, but what's the issue ? Not long ago they were complete strangers and the only thing that makes a relationship between them incestuous is that their respective parent married each other.
In the same fashion, if your parents are divorced, you're dating a girl whose parents are also divorced (or both of you only have one parent left or something) and somehow your dad falls in love with her mother and mary her, is your relationship with you girlfriend now incestuous and should now become a normal brother-sister relationship ?