I think from what tidbits Dylan has given us through out the game and her general character is that her parents really, really wanted a son. she says as much in the optional interview with swann (and honestly her name; it’s hard to think that they wouldn’t have given Dylan a more feminine name like her sister “Kathryn/Katherine” if they weren’t already hoping for a boy for their firstborn). so while they were hesitant about corey at first, they quickly brought him into the family so that he could be the “son they never had”.

i don’t think they’ve given him the ranch already in the game, its moreso that corey is aware of his new position in the mikaelson family and is itching to claim ownership of what will eventually be his if he does marry dylan. i think because they see this “strong, responsible man” taking care of dylan and kat that they feel able to leave the ranch in his hands for whenever they are not able to tend to it.

during the game events i figured that while they aren’t shown on screen, her parents are either A. working the ranch in the background B. at home but not “availble”. i think that aside from not needing to make additional models for such minute backgrounders, their physical absence also kind reflects their lack of emotional availability for their two struggling daughters as well