More than 7 signers per documents

Dear community,

I am currently setting up a document with Adobe Acrobat Pro DC (17.12.20098.240878) . I would like to have 9 assigned signature fields associated with 9 people/email addresses. While all this works perfectly fine with up to 7 signers, I  struggle with implementing the total 9. The "participant's role" field lets me select signer, signer1-6 so a total of 7 signatures.Same goes for the "date" field and the associated participant's role. Maybe there is a way to manually implement the missing fields. I have a hard time believing that 7 is the cut-off for the maximal amount of signatures.

Thank you for your help,

Georg