Requisition Approval for Project related purchase requisitions

• Client requirement is for "Research Sponsored" project type, they are assigning two signing authorities into the project module.
• The signing authorities are project manager and and alternate approver. Picture attached here showing fields from project module where we are capturing signing authorities.
• Client wanted to see approval notification should go to both managers parallel so either one can approve the purchase requisition.
• While configuring purchase requisition approval rules, I am able to only create notification action to 'Project Manager".
• Could you please help to find out solution, how can configure to send approval notification to both project signing managers?

• Following screenshots attached for your reference and review.