Is Subject To allowed with if listed with a realtor?

[Chris Lynch]

I currently have been reaching out to expireds on my MLS. This one happened to be a duplex. Anyway I had talked to the realtor and she said that he may be interested in owner financing. Come to find out he still owed 135K on the property but was open to the idea. He bought it for 165K and has only owned it 3 years..that being said I offered to take of the payments subject to because I had told him if he did sell it and pay the realtor fees he would not really be walking away with much at all and he agreed.

This was not my original plan to do a subject to, I was originally trying to get properties through owner financing. That being said, can I still do this if a realtor is involved? My guess is no or it is extremely difficult to do since it is not a "traditional" real estate sale going through a brokerage. 

I would really like some input on this if any of you have any idea. Thanks in advance.