@itonewbie I truly appreciate your consistent help with my tax questions.

Does the dependent child have any income that may otherwise fall within US tax net?  If not, I wouldn't file a F.8843.:     No , child did not have income. I found this today: UNIVERSITY OF CALIFORNIA, BERKELEY, 

Who must file Form 8843?
All international students, scholars and their dependents including spouses and children present in the U.S. under
F-1, F-2, J-1, or J-2 nonimmigrant status regardless of an individual's age, who are nonresidents for tax
purposes, must file Form 8843. Nonresidents for tax purposes must file this form with the IRS even if they received
NO income in 2023. 

The presumption is that the husband on J-2 has EAD and he substantially complies with the requirements for being so present pursuant to §7701(b)(5) and §301.7701(b)-3(b)(6) to be treated as an exempt individual.  On that basis, he'll file a F.1040-NR separate from the J-1 spouse. Got it, thanks

SE-income and employment income are US-ECI, which is subject to graduated rates under §1.  SE-income would be reported on Sch C and Sch 1 before flowing to page 1 of F.1040-NR. Got it, thank.

To be honest I did not see any part of Sch C that to checkmark exempt from SE since he is Nonresident!

May I have your help for this part!