Daughter is about to study overseas in Spain. She has an iPhone13 which is supposed to have "dual Sim" capabilities. So if she wants to buy and install a local Sim card in Spain, how do we know if she currently has a physical Sim card (for her regular US number) that she needs to remove, or if she currently has an eSim for her US number? In other words, how can we retain BOTH Sims on her phone so it will work with her original current US phone # as well as with a local Spain number she will get with the local SIM card? And how does she control this? Also, can she get the Spanish SIM card in the US before she leaves, and have it installed? Any advice appreciated. Additionally, we may activate the International plan on her phone to make sure all bases are covered, but if we can avoid the $100/month extra, we would love to. THANKS