There is bound to be disruption with these arrangements and below are some matters for consideration:
Government advice is that where parents live apart, children under 18 year of age can be transported tween their parents’ homes, provided of course that they are not showing any symptoms of Covid-19. It is up to the parents to agree what is and is not acceptable when they have the children, and what happens to home schooling and course work. They should be as flexible to reduce arguments.
Technologies like video calls can be used more frequently to maintain contact.
If one parent cannot see the children for health reasons, perhaps agree to give that parent additional time in the future to make up the difference.
If parents can’t agree on changes to arrangements, take legal advice or engage a mediator who can do sessions remotely.
In the worst case scenario, the courts can be involved but delays can be expected.