How to sync ringtones to iPhone?

Okay, so I do know how to sync my ringtones to my iPhone. My issue is that I created some custom ringtones from my computer for both my mom and sister a few years ago and put it on their phones.
My mom just got a new iPhone and her ringtones aren't on there anymore and I can't remember how I put them on there in the first place.
Is there any way I can sync just the ringtones from my itunes to her iPhone without erasing any of her things? She doesn't have music on her iphone.

I'm assuming that you're going to be using a different computer to sync the ringtones than what your mother's iPhone is already synced to.

You should be able to sync the ringtones without deleting all of the things on her phone as long as you do not sync anything else, such as music or apps.

First of all, make sure that you still have the ringtone files by checking in the folder that you originally made when you created them. Then, connect her phone, and go into iTunes.

Just to make sure that iTunes recognizes the ringtones, check in the bar at the top under the display with the Apple logo (if nothing is playing) and see if there's a tab called "Tones". If there's, than you're in luck. If there isn't, then unfortunately, I'm afraid that I can't help you beyond that because there are so many different possibilities that I couldn't possibly help you without being there with you.

But if it is there, click your mom's iPhone tab at the top on that same bar where Tones is. Then, when the screen with the summary of her iPhone appears, click the tab at the top that says "Tones", and check teh checkbox next to "Sync Tones".

Now, this is the important part to make sure that you mom's iPhone doesn't get erased.
Make sure that none of the other tabs have anything checked inside of them, because that would erase all of that type of media and replace it with whatever is in your library.

After you've done all that, go ahead and click "Apply" at the bottom right corner, and your ringtones should sync!