Another plot could be that the baby gets lost at the Camp Rock grounds. Shane and Mitchie then have to search everywhere, and in the process, they recall their own memories of the camp. The other campers could also join in the search. Eventually, they find the baby safe and sound, and it brings the whole camp community closer together. This would show the strong bonds within the Camp Rock family.
Perhaps the baby has a special connection with a particular animal at the camp, like a deer that always comes near when the baby is around. Shane and Mitchie are initially worried but then realize it's a harmless and beautiful connection. They could then write a song together inspired by this unique relationship their baby has with nature.
One idea could be that Shane and Mitchie's baby has an amazing musical talent that emerges at a very young age. Maybe they discover the baby can play a complex melody on a toy piano just by listening to music once. This could lead to cute moments of Shane and Mitchie being proud parents and also thinking about how to nurture this talent in a fun and age - appropriate way.