Probably the easiest and most flexible option for you.

Sara has an isdn link, which means she can link up to the studio of your choice (as long as they also have isdn). This is how the process works:

Sara talks to your producers via her microphone, in her own studio. Her voice travels through the isdn telephone lines and straight into your chosen studio where your production team record her voice.

You may decide you also wish to be present in the studio. Then, you and/or your production team, can direct Sara accordingly. It is as if she is in the room next door to you.

Travelling to and from studios is omitted saving time and money, and logistically it works out well for all concerned.

This process means you retain control of your project and ensure it turns out perfectly to meet all your requirements.