Go look on amazon for the SIM Adapter Kit (looks like $5 for Prime, little cheaper if you wait an unknown shipping time). It allows you to take smaller SIM cards and safely put them in larger-SIM devices. You can then use the SIM in your current device to get past the nag screen you're talking about.
I don't know the device to be able to tell you if there's any other way. But, a SIM Adapter Kit isn't a bad thing to have [especially at that price], especially if you continue to keep that device as a backup phone.
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