Hello, Jon!
There are several potential ways to do it:
Probably the easiest would be to add Additonal Fields to a Lookup field. Children Items are tied to Parent with Lookup in any case, and if you go to List Settings -> Column Settings for Lookup field(e.g. Parent), you can choose what other Fields from Parent you want to display:
- Additional Fields for Lookup.png (5.08 KiB) Viewed 1688 times
This is the easiest way as these additional fields will update automatically as soon as something changes in Parent.
A harder alternative might be to use a Workflow which will update Children with information from Parent when it changes. You can google more about Workflows and different things that can be done, but basic information can be found here -
https://support.office.com/en-us/articl ... 56eff4d9e3
Finally, another alternative is to use Microsoft Flow which comes included in Office365 if you use SharePoint Online, but can also be used separately. It's similar to Workflows, but easier to configure and use, but not all fields are supported yet. Read more about it here -
https://flow.microsoft.com/en-us/
I highly recommend option #1, but if you absolutely have to copy information instead of displaying it, Workflows and Flows might help you a lot. There is also an option to use JavaScript requests on item save to edit information in children, that is also possible, but even more complex than the other options, so I advice trying these out first.