How to insert additional line items on a quote based on a value on the existing line item

Summary:

Script to insert additional lines based on a value on a quote or a line item

Content (required):

Need script for below use cases:

Use case 1: Based on a quote attribute value, need add/delete line items against a quote.

Use case 2: A quote has a default line item. based on a attribute value on the existing line items. Need to auto insert additional rows and associate these rows to the default line item.

Example: On existing line item, I select a attribute no. of rows to be added = 2, and click a button, this should add two more line items say 1.1 and 1.2 and associate these lines to default line 1.