Currently we can hide some activity types from the Activity drop down menu in timeline but we cannot hide activities of the hidden activity types from showing in the timeline. Would it be possible to allow us to hide the activities in the timeline?

The business scenario is that we have activities and sub activities (Sub activity is actually an activity but it is a sub activity of another activity in business logic). We can hide the sub activity types from Activity drop down menu in timeline so users cannot create those sub activities from there . We only allow users to create sub activities from an activity which they should lie in. But all the activities and sub activities are shown in timeline which is very confusing. We only want to show activities in timeline. The users can view sub activities when you view the details of the activity they lie in.