Hi Gavin,
If you want to copy data from one model to another model, then I can recommend the following sequence of actions. First, please implement the RUNLOGIC BADI. Then, in the main script, launched from the source model:
1. Using RUNLOGIC BADI launch script in the target model to clear data for the required scope: *REC(EXPRESSION=0)
2. Copy values using *DESTINATION_APP: *REC(EXPRESSION=%VALUE%)
B.R. Vadim