API endpoint to add a member to a program

Hello,

we need to develop the following flow for a customer of ours:
1. Our platform creates a program in Marketo;

2. An user of our platform adds a person to our systems;

3. This person must be added to the synced program from Marketo;

The only way to manually add members to a program via UI is through a file import.
I'm looking for ways to do this through the Rest API, but I cannot find the right endpoint to do so.

Do you guys know how to do this?

Thanks.