No, I don't think you can change a SAS-supplied format. You can only create your own user-defined formats (where using the same name as a SAS-supplied format is not a good idea, see SAS Problem Note 18075), as you did already.
I'm not familiar with VA, but normally a format on a numeric variable should not prevent calculations. In any case it should be possible to perform the calculations before the format comes into play. The format could be assigned at a late stage, only for reporting purposes.
If there was no other way, I would then
But, again, I have never used VA. So, the above approach may be unusual.
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