Hi ER! Glad that was what you needed to manage your multiple IDs.
Just want to make sure that you are aware of associating devices and computers to your Apple ID, and the potential limitations that it can cause. The reason I used a different User Account on my Mac is because I did not want to associate my Mac under my primary User ID to a different Apple ID than my primary one. Family Sharing is one of the functions that will tie a device or computer to a particular Apple ID for 90 days.
Here is the relevant portion of a support article concerning Associated Devices/Computers:
Your iPhone, iPad, iPod touch, Mac, PC, or Android phone automatically associate with your Apple ID and iTunes when you:
When you try to associate another Apple ID with a device that was already associated, you might see a message that says, "This device is associated with another Apple ID. You cannot associate this device with another Apple ID for [number] days." Depending on when you associated your device with your Apple ID, you might need to wait up to 90 days to associate the device with another Apple ID.
I just want to make sure that you do not tie up anything for 90 days with an ID that you don't really want to use as your primary. Here is the link to the entire article: View and remove your associated devices in iTunes - Apple Support
Cheers,
GB