How to set up a new company as "contributor only"
Click the following link for instructions on how to add a company to the family list.
Once the company is added, select Edit Details → Select Family Group → Select Contributor Only → Save and Close.
Note: when adding a company, it is going to force you to choose a prefix. However, this is nothing to worry about cause it won't make any difference when adding the company.
When you post to the company in Detail Posting, make sure your Posting Filters1 are "Both" and "All Groups;" your Posting Options 2 says "Name" for Input By (since they probably don't have an envelope number); type what you used as the company's last name in the last name field of the Post To field3; select the company and check the Post to Preview 4 on the right to make sure it posts to the right family: