I don’t know if it’s correct to say it’s the only way. Certainly, Life360 geofencing, in conjunction with IFTTT, works well, I use it. It’s also true to say that the native IFTTT geofencing doesn’t work well, or at least it didn’t when I last tried it about a year ago.
Since going with Life360, I’ve read, on more than one occasion, that there are other reliable geolocation services that work well with IFTTT and Blink. Right now I don’t recall what they are, but there are others, for sure.
As for two sync modules, however you did the set-up for the first one, can’t you simply repeat that for the second one?
My set-up works so well I haven’t even looked at it for a year, so I’ve completely forgotten how I did it, but I know that when I did, I already had at least three sync modules, so I must have been able to pick the one I wanted. If I could pick it, then I could have picked another one, is the logic I’m applying here, so I’m thinking you could just repeat it for a second.
If you can’t do that, come back to us, and when I next look in, if no one has still come back with an exact answer, I’ll revisit my set-up, and try to add a second sync module.