Registration sets allow players to register for multiple leagues when going through registration. They will still have to complete steps associated with each individual league they are registering for, along with any global steps. 

Fees will be charged according to each league they are registering for. If each league has its own merchant account for each league, then the payments will go to whichever league they are registering for.

You can get to registration sets by navigating to setup->registration->registration sets. You will see the screen below. 

If you have already created registration sets, they will be listed here. To create a new registration set, click the add button and you will see the screen shown below:

Give the set a name and description. Click create and you will be shown the league sessions box where you add leagues to the set. Only leagues that have already been created will appear under the league drop-down field. Here you can edit league information such as registration start and end dates. 

After you click save to add the league to the set, you will see the screen below.

All the leagues that have been added will be filled into the league sessions box where you can edit, disable, or delete them. Click update to save whatever changes you have made