i think the grandpa is going to give the inheritance to her (or whoever from the cha family marries her), so they are going to start chasing her for bad reasons. we'll have to analyze the ml's (and that cousin of his she's in love with) actions and see if he was initially manipulating her...
ive got a feeling lucas' father is encouraging lucas to marry leah so that their family gets all the power (bc lucas' sister mentioned that the father doesnt like leah). lucas' feelings seem genuine tho - but no is NO!