Magic Users
I was intending for our first meeting to be next week but our current crisis demands otherwise.
Perhaps one of the other magic users with a similar power can fill in for your missing sister if you use a power of three spell. Or at the very least all of our magic combined might be able to locate the source and put an end to this.
I'll reach out to your sister and let her know about the meeting. Emma Swan -- if she is still here -- will need to be told that we've called for a meeting. She won't be able to see anything I've said here.