What all legal options exist in PA to reduce costs, taxes, commissions, paperwork, legal fees, etc. to obtain property from family member as well as get funds quickly into my sons hands so he can acquire another home in another state?

Background: My son has a mortgage on house and presently resides in it. He will be relocating out of state for new job. Obviously wanting to sell quickly, close on existing mortgage and having funds to purchase next home is needed. I am interested in buying his current house and making an addition and flipping it. I might be able to use cash/hard money to avoid a mortgage to acquire. I have an LLC and do various handyman and flipping work. Never been in situation of acquiring home from immediate family member before. Since he has a family and relocating is involved, there is flexibility in when and how they can depart, timing of when I take ownership, and them actually departing, etc. No inspections required as I've done most of the existing repairs required since acquired 2 years ago. For talking purposes here let's say existing house is worth $180k in existing market.