In this document https://confluence.atlassian.com/display/BAMBOO/Dependency+blocking+strategies we have have limited blocking strategy to work only based on source code updates

Dependency blocking only works when the plan uses a trigger configuration based on source code updates (i.e. Polling the repository for changes or Repository triggers the build when changes are committed). This feature will not work when a plan uses a trigger configuration based on a schedule or triggered via a parent build (when there are multiple parent plan builds in progress).

It would be nice if this can be extended to triggers based on a schedule or via a parent build.