Multiple Projects with multiple sales orders

Dear Community,
I have multiple projects with multiple sales orders and want to issue one invoice for all sales orders for one customer and always says: “Incorrect value: Project must be =”

Since Project is in the main form of Sales Invoice, it can hold only one value at a time. Please create separate Sales Invoice for each Project of the Customer.

Is there any hack to achieve this as Customer asking for Single Invoice for multiple sales Order everything is working except this error

if we need certain features are you guys able to create that for us?

You can post your requirements here.