To begin with, look at your sentence:
"Members of the 16th Lok Sabha worked harder in the budget session
than they have in the last 10 years, parliamentary data shows.
I recommend looking at it in two parts:
- Members of the 16th Lok Sabha worked harder in the budget session
- than they have in the last 10 years, parliamentary data shows.
Sentence 1 tells you that members of the 16th Lok Sabha worked harder in the budget session. The "budget session" refers to the present budget session, that happened just now, or during the 16th Lok Sabha, if you will.
Sentence 2 introduces a comparison- with how much they have worked in the last 10 years. Now, the idea behind using "have" is to introduce a continuum, a matter of fact that "has been happening" regularly over the past 10 years.
If you use "had" instead, it gives the idea that something HAS happened at a certain point in time, and then that's it. It didn't happen anymore. For instance:
They studied harder this term than they had last year.
Notice how "had" is used to indicate what they did just once, that is last year.
Again, if you now use "have" in the same sentence, see how you get a different meaning:
They studied harder this term than they have in the last five
years.
Here, "have" tells you about something that hasn't occurred just once, but has been occurring regularly over a course of time, that is five years.
It's interesting to note that using "had" in part 2 of your original sentence wouldn't make it incorrect, technically. There is a very fine line between using "have" and "had" to denote a continous action in the past tense. As I explained with my previous example, if you use "had" in sentence 2, it indicates that the members of the Lok Sabha had worked up until now, which doesn't fit in well with sentence 1.
And lastly, do take a look at this question on the EL&U site: How do the tenses and aspects in English correspond temporally to one another?. It should give you a clear picture about everything.
Please forgive me for writing whatever came to my mind with a total lack of organization.
This simply means that the author feels he has been writing whatever came to his mind without organizing the things that he wanted to write.
It says nothing about the organization he works for, the organization of his country's war effort, or anything else. It simply means:
I am sorry for writing all this in an non-organized way.
Best Answer
You have it right, and it would be they had three children if just one or two died too. Also right with birthing and "had" it would go: She had 3 kids. It makes sense in context and wont come off like they are dead.