Some updates:Today, I contacted two smaller brokers, and their...

Some updates:
Today, I contacted two smaller brokers, and their general response was that at this current stage, with the scheme not yet approved, and CBR unable to confirm its listing in the US, they cannot receive or transfer new MergeCo shares. I'll have to wait for the entire merger process to be completed before addressing this.
I have given up hope on trading CBR right after it lists, and I'll consider doing the share transfer after CBR is listed in the US.