Can I use two different Apple IDs?
At the moment using NotePlan with two different Apple IDs will be a challenge, due to the iCloud Drive or CloudKit synchronization. Both sync methods are bound to a single Apple ID.
Alternatively, you can use Dropbox sync in the preferences. However, this sync method is not recommended and has known problems with moving or deleting notes.
You can track the following feature requests, which might become a workaround for this problem: