I would say yes, go ahead and designate a backup. Make sure both of these ladies know the situation, no one likes to feel second best. I actually had to call on a backup moh, as my best friend wasn't sure she had the finances to make the trip. So now my "new" moh has been awesome. Helped with soooooo much. My best friend knew I had to do it, there are no hard feelings. Good luck with this! I'm sure everything will work out great for you!