Assuming these are zwave switches and not zigbee, the Aeon Minimote is perfect for this. It’s a small handheld remote that can include, exclude, or associate two zwave devices on the SmartThings network as long as they don’t require encrypted communication. So light switches, thermostats, relays, motion sensors, all good. But not doorlocks.
There’s an Aeon Minimote included in the ST lighting kit, otherwise you can buy one for about $30. Also makes an excellent “button controller,” and as such can also change modes and toggle zigbee devices (using the hub as an intermediary).
Also, newer zwave devices other than locks can often pair via relay, so as long as there is another repeating device close by, you may be able to pair. This should work for all zwave plus devices, for older ones it just depends on the specific device. Older devices will usually describe this as being “NWI capable.” (Networkwide Inclusion.) Sometimes the pairing method is slightly different, so check the manual.
Here, just as an example, a device that has a different pairing method for pairing directly to a controller (hub or Minimote) or pairing via repeater (NWI):