Hello, and welcome. I am a licensed attorney and happy to assist.
The answer is likely located in the document itself. If not, there is still a workaround.
If the document states that the "property owner" has the right, you could be construed as the intended beneficiary as it could be argued that the right runs with the land. If the former owner was only designated by name, the answer will turn on whether or not the right is assignable. The allowance or prohibition of assignment should appear in the document granting the right.
If neither of these bode well in your favor, the former owner could purchase the land jointly with you, with your funds/credit, then quit claim it back to you. The two of you would want to memorialize the agreement so there is no funny business or complications.
I hope this helps. If you need additional information or clarification, just let me know and I'll continue to provide assistance. If I have addressed your issue and/or pointed you in a positive direction, please let me know that, as well. Also, please remember to leave a positive rating when prompted, as that is the only way attorneys on this site are credited for the help we provide.