AdobeSign vs Adobe Reader

Dear all,

I solve one of my questions how does work AdobeSign, because from other companies with who we are cooperative has offered to use Adobe Sign, but we currently sign all documents via Adobe Reader.

Is possible that other 9 companies will sign a document via AdobeSign and we are as the last one will sign it via Adobe Reader or all document signed via Adobe Sign must be completely signed via Adobe Sign?

I´m sorry, I found so many information about that and I´m confused about that. Or need I have Adobe Reader PRO for that?

Thank you