Hi Olivia,
There is no way to combine two environment directly. What you can do is either you replicate the Planning model to your IFRS environment or the complete IFRS enviroment to the Environment where you have your planning model. Rate model will be there in both the models, so no need to replicate that.
You have to see which will be more easy and make the replication.
Hope this helps.
Regards,
Kalyan.