SS process

I am in the middle of doing my first SS.
My client is behind 2 month on both and no lis-pen has been
File against the property. I am confused about who gets what when.
For example do I send a complete SS package to both simultaneously?
Or do I get the 1st to approve my offer subject to the 2nd lender’s approval,
And then send the approved offer to the 2nd to negotiate their price.
If someone has experience with SS please explain the sending process.