If I understand your question well, there are three possible scenarios as follows:
1. Billed airline not suspended – normal processing applies.
2. Billed airline not suspended but becomes suspended during invoice processing – in this case the process SIS will follow is described in the ISPG v3.2, Section 7.7/Suspended Member.
The invoice will be presented normally, but it is flagged as suspended, which means settlement may or may not occur depending on whether the ICH has access to sufficient funds to cover the suspended airline’s debt (which could be from a security deposit or from other sources of funds).
3. Billed airline is suspended before the current period – in this case the invoice is processed normally, but the suspended flag is set.
a) If the invoice has SMI=I it will be routed to the ICH for recording purposes. It will show up on the Suspended Form 3, but will not be settled.
b) If SMI=A no file will be sent to the clearing house. The invoice will be presented to the suspended member in the normal manner for bilateral settlement as may be agreed between the airlines unless the billing airline expects early reinstatement, in which case it may choose not to chase bilateral settlement. It will be able to resubmit those invoices in the event the suspended airline is reinstated. The invoices will continue to be presented to the suspended airline unless it is terminated from SIS for any reason (including default). After that point, any invoicing will have to be outside SIS.
I hope this clarifies your queries on the topic. If my understanding of your question is not correct, please clarify and I will be reply again accordingly.