I have a couple questions regarding bill of material that a search of the forum couldn't answer.

1. In this case the BOM made what should have been Item 11, Item 14. It skipped the number 11 entirely and continued with Item 12.

Any idea on what causes this or how to avoid it in the future?

2. Related to my first question. Can I change the item numbers without breaking the link?

For example; I would like to change Item 9 to Item 6, and have the BOM to continue setting the rest of the item numbers as it normally would.