究竟The Lee family用have move或has moved 那一才對

Family is singular when they are used as collective noun.
Example : My family is moving to Canada next year.

Family is plural when you are referring to the members of the family.
Example : My whole family are working in Hong Kong side.

The Lee family have or has ?? – It should be definitely : The Lee family has moved to the new flat.
Explanation :
- The Lee family is a collective noun, so it is third person singular.

It depends on what the word 'family' above refers to.

When the 'family' meaning a HOME (家庭), then 'The Lee family' will be A thing. That means you need to add "s", "es", "ies" and so on. So for this definition, you can use 'The Lee family has moved to the new flat'.

But in another case, if you want to define the 'family' meaning a group of people (家人), 'family' this word would be a PLURAL. That means you should use 'The Lee family have moved to the new flat' better.

**P.S. In English language, this kind of situation always occurs. Add "s" or not, single or plural, are always depended on what you want the word defines. (As for sure, the words must own the meaning you want to define.)

family - is a countable group, consisting of parents and children.
I think it should be:

The Lee family have moved to the new flat.