Running Mines of Phandelver, need help with setting up in ROLL20!

I have been a DM for 15 years but I am no computer programmer! So this is a huge learning curve and I am grateful to this helpful community that has been stepping in as all the socially distanced gamers flock to the virtual table top!  Yesterday was our trial run of just seeing if we could all get online and get control of our tokens - we could not! I have two kids in my game who noncommittally play as their parent's characters sometimes, so I assigned control of these single characters to two separate players (1 parent + 1 kid) . In both instances the feature did not work, and the token only responded to the player who I had assigned it to first, and not the player whose name I wrote second (leaving 2 distressed kids feeling like they were not being included!)  Is there something I could be doing wrong that the tokens could not be controlled by both players I had assigned it to? I also considered working around it by just giving the kids their own tokens to move around the board. (I don't even care if duplicating the PC's throws off the game mechanics by delivering less XP in each fight and thereby slowing levelling, my goal is to just get everyone playing, or at least, for the kids, the impression that they are playing!)  I tried pressing the "duplicate" button on the PCs, and then assigning that duplicate (which appears in everyone's journal) to the kids, but somehow, the player I had originally ascribed control of the orginal PC was SOMEHOW still able to control this rogue duplicate, even though he'd never been given control of the duplicate! I am going to launch a new game today and see if we can at least get correct control of our tokens this time. Do you recommend this method of duplicating PCs so my less-attention-span younger players can have token characters? Will this work? Should I just assign them control of any token that they want and make up stats for them?  Is there a reason I can't get the tokens to be controlled by more than one player? Is there an easy way to import more PCs into this game, functioning character sheets and all? (I have also researched importing character sheets - but I have not figured out if it is possible to do in a pre-bought module. The way the character sheets are pre-built is a godsend at this time, and I would be loathe to build a character from scratch in a platform I don't understand yet!) Thank you for your time!

What is almost certainly happening is sue to how tokens are assigned to characters. When you set up a token and link it to Aragorn, that single token is linked to Aragorn. If you drag another instance of Aragorn out of your journal tab, he will not be using that token. Not yet. You must make that token the default token for Aragorn, by selecting it, editing the Aragorn character sheet (press the Edit button in the upper right) and assign the selected token as the default token for the Aragorn sheet. (You may need to delete the previous default token for Aragorn to make this happen. Now when you drag Aragorn from the Journal, the default token will be the one you assigned. Saving the default token is akin to saving your work. It must be the last step. Now, let's say you duplicate Aragorn and name the new sheet Boromir. Boromir's default token is still the same one you linked to Aragorn. It points to the Aragorn sheet, even though it is attached to Boromir. You must create a new token for Boromir, link it to Boromir, and save it as the default token for Boromir's sheet If all that was as clear as mud, here is a video I made that may help with understanding how default tokens work. Roll20TnT Linking Tokens and Journals