Ollie will bark at my partner and I if we are playing basketball as he can not readily join in ...too big and heavy a ball😁. He is so used to bring included in all other games like catch, football, frisbee, running, cycling that I assume he feels frustrated when he is not in on the action.
Hierarchy issues...well I, unlike a lot of others, certainly believe these can exist in family and dog dynamics but I would be more concerned at a dog displaying intolerant behaviour such as snapping at children who came near them which I would consider a sign of a dog attempting to pull rank. There's a lot more to this in terms of children's unpredictable behaviour which can make a dog feel uncomfortable of course, but an acceptable pet behaviour then would be to move away rather than to try to regulate the children's behaviour with aggressive responses.
If you're not experiencing behaviours like this I don't know that you need to think it is a hierarchy issue rather than a frustration issue and general elevated arousal at the activity that is going on. (But i also personally believe you have had good general advice about getting kids to feed and train for treats etc)
You can possibly redirect her so she is engaged in an activity of her own whilst the kids are playing, or better yet get everyone involved in a game of 'find it' where the kids show her a toy, tell her they are doing to hide it and then shut her in a room whilst they tramp through the house and garden to find the best hiding spot. Release her and ask her to find it ...kids can help guide her if she is struggling ☺ can play this with treats too. Kids can plant them in various places. Tell them they have to go through all the rooms and make noises opening and closing drawers etc as she will be listening for them and will know to go straight to the right room if that is the only one they go to.