GST to SST tax move

Hi Gurus,

Need your suggestion. Malaysia is moving from GST To SST starting 1st September 2018. For that we have created new SST condition type, added it to our pricing procedure and maintained as 'required'. The settings are working fine for new transactions however we are facing issues when we have an old transaction which was billed in GST and is now canceled and rebill after 1st September. In such cases only GST should be applied on document but since we have maintained SST condition type as 'required' system will deem rebilled invoice as incomplete due to missing SST condition record. If we create a dummy SST condition record with 0 rate then billing document will have GST @ 6% and SST@0% which is incorrect since one document cannot have GST and SST as per business finance team. Has anyone encountered this issue? If yes can you please suggest how best this can be handled.

Regards

MN