Based on the given information, here are the subject pronouns that refer to the people listed:
1. Roberto: él (he)
2. Susana: ella (she)
3. Carlos y Carolina: ellos (they)
4. tú y yo: nosotros/nosotras (we)
5. Miguel y tú: ustedes (you all)
6. Elena y Gloria: ellas (they)
7. Marta y Ud.: ustedes (you all)
Please note that the subject pronouns "ustedes" can be used to refer to both a group of people in a formal context or multiple individuals in an informal context.