Currently the only way to alternate between decimal delimiter styles - dots or commas, in business central is via the Region setting in My Settings menu.
You can use one or the other, but not both at the same time.
This does not cut it for companies that work with countries using both styles and is slowing down the document exchange.
In addition there is absolutely no way to alternate the decimals with AL code because the My Settings do not have a designated table and cannot be subscribed to.