Combine PDF Documents into one document and attach to an email

Dear all

Attached form has a User form that opens automatically when you open it, on the big list (ListView1) you can multi select the lines by holding CTRL key down + clicking mouse right button, It will highlight the selected lines then when you click the "Select Invoices" button it will list the selected invoices on the small window (ListView2) at the top. From here when you click the "Multiple Attach" button it will find each selected invoices' directory path at the excel Sheet("Multi") Colum F then convert each of the founded invoices to PDF and one by one it will attach these PDF invoices to one email.

What I am trying to achieve is merge all the PDF invoices into one document then attach that document to the email. Can this be done?

Thanks in advance