Hi Ken
When the surname or Last Name at Birth (LNAB) is identical, then merges always have to go from the largest number to the smallest, the system won't allow it to happen in reverse. So this merge will have to go from Lefebvre-2586 > Lefebvre-534.
However after the merge is completed usually both profile managers end up jointly managing the profile, and you can expand it and add more detail and sources then.