As Jim,DepressedDerek and tb1uk have stated, you have a number of options to consider for submitting these documents to the tribunal. It matters not whether you or CAB sends them as the tribunal will make a judgement based on the evidence and not who sent or delivered them.
Recently, with no support from CAB or a WRO, I had no choice but to represent my son at his recent appeal. As a result of a deterioration in his condition, he had unforseen treatment 2 days before the appeal and letters showing further tests over the coming weeks. I had no option but to hand these to the Clerk on the day. I am pleased to say that we won our appeal and the board were very sensitive and sympathetic.