Any bonding issues are the fault of the owner. Dogs bond with whomever spends the time with the dog, they will bond with more than one individual or even more than one person at a time. Just like people, dogs can have a number of "best friends" through their lives. This idea of a dog bonding with one individual to the exclusion of all others is mostly a literary myth. Look at those dogs used for military/police work or those as service dogs. These dogs may spend the first couple of years in training before meeting their final owners and I don't think anyone can honestly say the dogs do not form a bond with the owners. There is the rare dog/owner pairing that doesn't work out but the dog generally finds a place with a different owner whether as a service dog or regular pet.
I've had dogs that have spent anywhere from 7 months to 3.5 years with another person before they became permanent fixtures around my house. None, even the 3.5 year old had any issues bonding with me. They have all retained a bond with previous owners/handlers for a period of time afterwards. It is said wolves will remember previous pack members up to 5 years after separation so I would expect domestic dogs to be little different.
The same can be said of those dogs I had for varying periods of time before the dogs found/returned home. Those dogs bonded with the previous/new owners just fine though remembered me afterwards too. I had to take a stepson's K9 the first time he went on vacation as his employer had not thought of what to do in this situation. The dog and I got along prior to this but after the week, that dog would do anything I asked of it. I think I miss that dog as much as my stepson.
So, don't worry about any bonding issues with a new dog or a current dog that spends time with someone else. There may be some time needed to make the transition but it won't be long if you spend time with the dog. The general rule is to keep the dog on a leash at first and start from the beginning with obedience. Work up from there in small steps in controlled areas until it minds appropriately then take it to a less controlled space as the dog understands and obeys. Depending on how often you work with the dog, the quality of the work, and the intelligence or desire to please in the dog, it can take a very short time to develop a bond.
Don't worry about any bonding issue, the problem is in your head. If there is any problems they are most likely to be due to the new owner and some training education of the owner would be necessary.
