In the desktop version, it can be entered in forms mode with no override necessary. For the online version, you would need to use the solution by Steam Train above which states:
Someone else had this issue.
....what worked for them was to take the tax-exempt $$ for their own state, and put those on a separate form....designating all as being from their home state....and then the original form would all be designated as "Multiple states"
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So if the combined $$ were in box 12 of a 1099-DIV, the NY (or CO) person would subtract the NY (or CO) $$ from that original combined 1099-DIV...and put those $$ in box 12 of a new separate 1099-DIV....marking it all as NY (or CO)..... and the original 1099-DIV would be marked as "Multiple States"
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