If your Motorola expert is the one who configured the system, do they know that you are trying to get some inexpensive (and likely not FCC type accepted) radios on the system?
Do you have access to an existing Motorola codeplug? I'm assuming that you already know the frequency, color codes, and talkgroup ID's of the system. There are settings beyond that which can cause you problems if the sites are configured for Privacy.
While the DMR Motorola radios are made to be compatible with DMR Tier II standards, not all features and functions are always set to those standards. Motorola has some proprietary features that operate ' above' the DMR floor, and are not going to work with your less expensive choices.
If you've got an expert - they should have explained that to you already, or at least told you how the system was configured.