Is layoutB based on the same table as layoutA? If they are you should be able to just use the go to layout script step and you will have the same found set and be on the same record. If layoutB is based on a different table then you should be able to use the go to related records script step to get to layoutB. If it is not working as you expect here are a few things you could check:
1. Are your merge fields (eg. clientName etc) meant to be looking back across the relationship to the tableA? Then they should be <<tableA::clientName>>.
2. What is the relationship between the two tables? Is it based on the clientID field?
3. Are you creating a new correspondence (tableB) record each time you do one of these letters? If so, does your relationship take you to that specific record or to all the correspondence records for that client? If so, has the new record in tableB been created before trying to go to it via GTRR?