I don't think you will need a TMS in site B as long as it has a separate Exchange domain. You can add the Site B CUCM into the existing TMS, such that it discovers the registered endpoints. we have a TMS which supports 4 CUCM clusters across the global location (AMER, APAC & Europe) regions. We have a global exchange domain through which it works well for OBTP with WebEx CMR.
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