Hi everyone!
This is my first time to post a question here.

I am working on a historical population dataset. This dataset is a triennial population register records. The dataset only contains records on year 1792, 1795, 1798,1801,1804,1807,1810,1813…1837.

I used tsfill function to change this dataset, making every person has a full record in each year. Therefore, 1793,1794,1796,1797 and so on are years generated by tsfill function.

My goal is to calculate age-specific marital fertility rate. Now I only have a variable for predicting whether this woman will have a child in next three years.

e.g. If No.1 first-married woman has a nextboys that equals to 1 in year 1792, she will give girth to a boy in 1792, 1793, 1794. In this case, 1793 and 1794 are two years generated by the program. I fill the blank with 0.

The following is an example of a subset of the dataset.
personid year age married nextboys groupid
1 1792 34 1 1 1
1 1793 35 1 0 1
1 1794 36 1 0 1
2 1792 23 1 1 2
2 1793 24 1 0 2
2 1794 25 1 0 2
3 1801 18 1 1 3
3 1802 19 1 0 3
3 1803 20 1 0 3
3 1804 21 1 1 4
3 1805 22 1 0 4
3 1806 23 1 0 4
4 1825 26 1 1 5
4 1826 27 1 0 5
4 1827 28 1 0 5
As we can see, we don't know in which exact year a woman gives birth to a new boy in the next three-year period. Take group 4 as an example: No. 3 woman has two records in this dataset in year 1801 and 1804. I used tsfill to fill blank years. No.3 woman has a nextboys at 1 in 1804. She will has this boy in 1804, 1805 or 1806, but we don't know which year.

I want this table look like this through reshuffling the dataset:
personid year age married nextboys groupid
1 1792 34 1 1 1
1 1793 35 1 0 1
1 1794 36 1 0 1
2 1792 23 1 0 2
2 1793 24 1 0 2
2 1794 25 1 1 2
3 1801 18 1 0 3
3 1802 19 1 1 3
3 1803 20 1 0 3
3 1804 21 1 0 4
3 1805 22 1 1 4
3 1806 23 1 0 4
4 1825 26 1 0 5
4 1826 27 1 0 5
4 1827 28 1 1 5

The value of nextboys, which will be randomly assigned within each group. Through this I can have a dataset simulating the real situation. A woman has a record of giving birth a boy in the exact year.

I would be much grateful for any suggestion and answer on this question! Thank you very much!