One 1099-NEC is larger than the others, so we cannot just allocated them to each other, but need to split the income from this particular client.
If you are filing a joint return, then all of your combined income goes on ONE Form 1040. Why are you trying to split up the income by spouse? Whose name is on the 1099NEC?
We're only filing one 1040, but TurboTax and IRS recommend splitting husband-wife income into two separate businesses so that each spouse is earning SS credit. The 1099-NEC is made out to a sole proprietor business using our last name (dba).
You can still split the one 1099 NEC. Each one of you will report the same 1099 NEC on both of your Schedule C's and cut the income reported Box 1 in half for each of you to report on your own Schedule C. You would also report half-of the expenses. just think of it as one Schedule C, but divided in half. This is the simplest illustration i can make.
Reach out if this doesn't fully address your issue.