Is this driving anyone else crazy? You see a sim walking by and try to initiate a conversation, but they just keep going and the action hovers in your queue for a while before disappearing. Then so...
The sims 3 had this option but idk if the sims 4 does, you can try looking through the options menu to see if you can give them lower free reign. If there’s nothing like that in TS4 try pausing, then teleporting your sims to whatever object or sim you want them to interject with using the “testingcheats true” cheat and then get them to interact with it/them, also keep your eye on the task bar just in case anything else pops up that your sim wants to do so you can cancel it.