The topside unit can only communicate with one locator at a time.
However, there is a possible solution in the case of the U1 locator (or the S1 locator for G1, which is not available for G2). Seven channels are available, and thus up to seven locators can be used together on different channels, but you must then switch between channels periodically in the topside unit; you should evaluate whether this is appropriate for your application.
The channel can be changed in the GUI (‘Settings’), or programmatically via the API. An overview of the channels can be found at the following link:
The API documentation can be found at the following link.
This solution does not apply to the A1 and D1 locators, as the channel used by these is set by the topside unit to be the same as the receiving channel.