Combining households has many benefits: less hassle running back and forth between two residences, less worry about Dad eating well and remembering his meds, more family social time for him, cost savings on rent and utilities, etc.
But if things do not work out, disentangling could cause hurt feelings and damage your relationship. Consider these questions before you move in together.
Relationships and life style
How do you and Dad get along? How does he get along with others in the house? How will he fit in with household routines? Will he eat what you eat? How will he cope with children? What about pets? Will he join you on vacation? Can you set boundaries and negotiate when issues arise? Are others in the house up for this change?
Physical space
Can you accommodate him and still have privacy? Will he have his own bathroom? Sitting area? TV? Do you need to install grab bars or a riser seat on the toilet? Is there space for his clothes and possessions?