Can a COBRA beneficiary drop his depedents mid-year?

[karen/benefits]

What is the name of your state? Washington

My brother and his family live in Washington state. He has covered himself and his family on COBRA for the last three months but can no longer afford the steep family premiums. He has lined up coverage under an individual plan for his wife and kids but must keep himself covered under COBRA since he has a pre-exising condition. His employer told him that he has to wait for Open Enrollment since there is no family status change associated with his request.
I know the COBRA regs state that beneficiaries must be given the same opportunities as active employees, but are COBRA beneficiaries supposed to be under the same restraints? He's not paying his COBRA premiums with pre-tax dollars so is he subject to section 125 restrictions/regs? Isn't each dependent considered a beneficiary in his/her own right? Could the wife and kids each send a letter dropping his/her own coverage, essentially leaving my brothers coverage intact as single coverage?