Are both sentences correct here: I'm having lunch with my cousin and/then after that

[B45]

Are both sentences correct here:

I'm having lunch with my cousin and/then after that I'm free so I might swing by to check out the event.

 

[Charlie Bernstein]

I only see one sentence. To make two, you need another period and another capital.

 

[B45]

Sorry about that, I meant to write:

I'm having lunch with my cousin and after that I'm free so I might swing by to check out the event.

and

I'm having lunch with my cousin then after that I'm free so I might swing by to check out the event.

I think they mean the same.