I'm not completely clear on what you mean but I'll try to describe scenarios.

Say you have a list of items and for each item you want to createa subcase. You then use a flow with the "Split For Each" shape and configure it to iterate over your list of items. You can use when rules to decide if the subcase should be created or not and you have access to the index of the items caused the subcase to be created.

You have the Split Join shape for starting different type of sub cases on your parent case data.

You have the smart shape "Create Case(s)" you can use in a flow or subflow to stear the creation of sub cases.

Please look into the help and documentation for help on how to use thease shapes.

Hope this helps.

You can use Copy page data to new subcase or data transform to populate the data to sub case other than data propagation configured in case type rule.

Is there a reason why you are copying .Hoken(page list) to the child case?

Ideally the fields on each record of the page list in iteration should be mapped to some individual properties in child case. This can be achieved using the data transform option provided with the create case smart shape.