is it possible to develop a condition to add certain number of records in the child's table based on a numeric input in the parent's table?

Raghda,
You may be able to do this with a webhook.  You'll need a trigger for the webhook and I don't think that change in a summary field would work.  Maybe you can do something with the details table update that triggers inserting records in the misses table.
Neil

This can be done for a limited number of children with either Actions which are easier to set up then we're parks or WebHooks.

I could describe a set up using Actions as long as the maximum number of children to be added was less than 10.

Basically you would just set up an action to add a record if the number of children to be added equals one.

Then you set up another action to add a record of the number of records to be added equals two, then you just continue that all the way up to 10.

I believe that there is a limit of 10 Actions per table. There is also a limit that you cannot fire more than 10 actions per Second.

If you need to get above 10 children, then you will need to use Webhooks and the complexity of setting that up is probably beyond what anyone is willing to answer on this forum.