No — Inform Direct does not currently support uploading a spreadsheet or CSV to bulk-populate a share allotment. Each shareholder must be entered individually.
For allotments to several shareholders at once, the fastest route is the multiple allotment screen: under the Share Classes tab, select Allot new shares, provided all shares are the same class, allotted on the same date, at the same amount paid per share, and paid in cash.
To speed this up, prepare the full list offline first (name, address, number of shares) so each entry can be typed in quickly without needing to look anything up mid-process. If your shareholders don't meet the same-class/same-date/same-price criteria, they'll need to be entered as separate allotments.