HMR to match rtp port on re invite

Hi

I have a scenario where by rtp port changes mid call causing dtmf to drop

Ie user calls external and is prompted for drmf, i see the dtmf get to the sbc but the sbc does not forward it onto the provider because the rtp port is changed midcall due to a re invite been sent to the sbc, is there a way to avoid this maybe with an hmr that would match the port of the initial invite to the port in the re invite?

Thanks