Dynamic sub tasks creation on the fly based on user input or attached file contents

per our business process we currently create a sub task manually for each member info (name, ID, address, contact number, etc.) entered in a custom field on the parent ticket and that we assign the sub task to the respective user (member) for tracking their work and closure comments. We have accommodated up to 6 custom fields, so typically in some cases 6 sub tasks would be opened and assigned to each individual user.

In a rare scenario, the list grown to 30 (max that we seen) and we managed the member info in a spreadsheet attached to parent ticket then followed by opening a sub task manually for 30 users, which became cumbersome and churn for our team who manages the sub task creation process.

In light of this new scenarios, we would like to find ways in automating the sub task creation process based on the list of members in the spreadsheet attached to the parent ticket. It would be really appreciated for any input and suggestions on tackling this complex requirement. My thought process is to have a tab with 30 custom fields for input entry of all members on the parent ticket rather attachment then using some custom automation have sub tasks created and assigned to each member entry but do not have a clue on how to achieve.