I work part time (three days) and DH works full time (five days but long hours each day). We have both WFH since March. We have two DC, one with severe SN.
During the first lockdown, when we had no childcare, I approached my employer to agree alternative working hours so that we could each work and take turns looking after the Dc. Thankfully they agreed, because they needed me to work (we had loads to do) and were happy that I was making a proposal.
What we did was: I worked 6am-9am, DH worked 9-12noon; I worked 12noon-2pm, DH worked 2pm-6pm; I worked 6pm-8:30pm; DH worked as many hours as he needed to after this, and I worked whatever more hours I needed to after the DC were asleep. Sometimes we both worked until midnight.
I worked two weekdays and one weekend day (normal working hours on that weekend day, so 9-5 or so). DH worked all weekdays. We had one day together as a family at the weekend.
It was really tough, but we managed, and I still don’t know how else we could have done it.
Just setting it out here in case it helps anyone else.