Once a BDC is added to or created within a top-level block design diagram, the tool automatically detects when a change is saved to the source block design of BDCs. A Refresh Changed Modules banner pops up in the top-level block design as shown below. The user is then allowed to sync the changes made to the BDC to top-level block design.
Figure 1. Refresh Changed Modules Banner
Note: Syncing changes between BDCs and a top-level BD is only supported within the same Vivado process.