Difficult construction with Past Perfect + have to

Question

I'm a little bit confused with grammatic construction which includes Past Perfect + "have to".

The first question which appears here is: if this construction is grammatic or not?

The law changed in October 2018 and before the change the vehicle drivers had had to have a document of liability insurance on them.

The second question: can we use the word "before"? Doesn't it interfere with the usage of Past Perfect tense here?

Also, the third question is: can we somehow blend Present Perfect with Past Perfect here (if the first part of the sentence is connected to the present and the second is connected to the past), in this very situation?

I'm almost sure that mixing Present Perfect (which is not connected to a specified moment in time) with Past Perfect (which is connected to the unspecified time before another event in time) might be ungrammatical.

But in this case, what other kind of grammatical construction we can use to say the same (when the one part of the sentence is connected to the present but second part must be connected to the past)???

Example:

The law has changed and before that change the vehicle drivers had had to have a document of liability insurance on them.

Is dividing of the sentence a good idea (???):

The law has changed. Before that change the vehicle drivers had had to have a document of liability insurance on them.

I apologize for silly questions and thank you in advance for your response.

Answer 1

The law changed in October 2018 and before the change the vehicle drivers (1)had (2)had (3)to have a document of liability insurance on them.

This is correct and could be heard in normal speech without anyone having any difficulty with it.

First of all you must disentangle the three different meanings of "have".

1. had (the simple past of the auxiliary verb "to have")

2. had (the past participle of the verb, "to have [to]" which indicates compulsion)

3. to have (the infinitive of 'to have' meaning to possess)

The law has changed and before that change the vehicle drivers had had to have a document of liability insurance on them.

The law has changed and since that change the vehicle drivers have had to have a document of liability insurance on them.

EDIT - I made an error. I've corrected it. (2) is the past participle of "to have [to]"