It is easy if you are a manager to skip your direct reports and request something from their direct reports.
And it is hard for them to say no, because you are boss of their boss.
But it creates many problems. You can put into jeopardy work you do not know about that will be postponed.
You also indicate you do not trust your direct report to manage his team.
Just do not do it unless it is absolutely necessary, and even then at least inform your direct report that it is happening.