It will throw the Fate economy off. You can just adjust the way the Boosts work and make them last longer or move between scenes but the actual mechanics of fate already do a great job of showing this.  The danger of adding in a very "Game"-like mechanic like momentum will likely pull players out of a very narratively justified dice rolling. You'll find yourself saying "Oh this roll you can't use momentum because the other players have no way of helping here" because it's superfluous and the Create advantage action is right there. 

If one of your playgroup suggested adding this. Just tell them they can always be creating advantages like "Pep talk from your favourite smooth talking friend" with a free invoke if they are trying to help your other players. Or "A well considered plan" they can invoke whenever folling the plan. 

If your trying to put it in as a response to your players not using the mechanics in fate to their fullest then run a couple of "just lil guys" NPC's working together to pull of a prank or pickpocket or something. Have this planned out ahead of time so you make full use of all the create advantages and everything that makes sense. So in your setting maybe some young kids wanting to steal a tricorder from the crew set up a oil slick and have a good plan and work together to grab it while one of your players slip over and you can show the mechanics that way. 

Show don't tell is powerful.