Here is a roughly drawn floorplan with dimensions.

Just a me thing but yikes the inspo sink would be a huge pain - esp for teens who have hair products and body products and need loads of counter space when getting ready

I am not sure how that change will improve function 3 teens sharing will always be a big deal and I see no benefit for the change of sink area. Then you lose storage which IMO is a much bigger issue with 3 sharing a bathoom . I lkke the space as it is I think it is the best you can do without a huge redo of the whole area around this space . Are you prepared to do that ? I think it is just fine as is . The kids will be gone and sooner than you think they have handled up to now .

I think the old design was better for 3 kids sharing, so one could be showering or using the toilet with the inside/second door closed, while another one can be using the sink or drying hair. The vanity area doesn't have to have a door, unless you kids leave a lot of clutter and you would like to close it off sometimes.

For even more storage of everyday toiletries use large mirrored recessed medicine cabinets. I have used several from Robern over the years.

For 3 teens, stay with the original plan. Just update the materials. Do they actually need 3 sinks? You may be able to do 2 sinks. Just offset the one on the main vanity so that someone can be brushing their teeth and someone else can be doing their hair. .

My two teen girls share a bathroom and the toilet and shower are separate and it’s great. One can shower while another gets ready etc. For three it would take a bit more timing planning but much Tue same.