How do the new Covid tier restrictions impact on children with separated parents?

The new Covid restrictions provide an additional challenge for children who have separated parents. Whilst it was clarified during the national lockdown that children were able to move between their parents' homes, are children now able to move between tier locations? For example, a child might have a mother living in Liverpool, which is in Tier 3, and a father living in York, listed in Tier 2. 

Despite what Boris Johnson said during the press conference on Friday, children ARE still able to move between their parents' homes as this is one of the exemptions. The rules on this topic have not changed since they were first implemented in March and allow movement between homes regardless of location “for the purposes of arrangements for access to, and contact between, parents and children where the children do not live in the same household as their parents or one of their parents”.