My personal opinion is don't.... Can a study nook or area be added somewhere else? The room looks too nice as is...

We are wanting to do the same thing and have been having trouble finding examples of others using a light roof with black windows as it seems the done thing is dark roof dark windows etc. But I've found the following here on Houzz which I think shows it can work. I love the interior look of black window frames because they "disappear" and allow the view to take centre stage. Alternatively some window manufacturers can produce a different colour on the exterior and interior for you (although I think they are only on double glazed units).

How much do your like your pelmets? I would remove them. Paint beside table and chest of drawers to refresh it and create new look . You can add a large colourful rug under the bed or any rug you like and get the bed linen to go with it. Couple smaller lamps on the bedside tables or two small pendants above each bed side table. Declutter, take rubbish bin out.

i was wondering about a downstairs front door but then how would you use the upstairs entry and what about potential loss of the grandparents' bedroom and space taken away from the garage and storage... different internal stairs meant enlarging the whole downstairs floor area (and changing the roof) and sacrificing space needed for the new upstairs deck and future pool (and extending further into the yard encroaches on the neighbours' views) but the old front stairs can be lengthened to maintain the original look of the house and you'll find that friends and family will more likely come in through the garage or rumpus room and the old front stairs will be used for only very enthusiastic sales people and photo ops but you do need to confirm all the dimensions on the original floor plan as the room sizes are inconsistent and an accurate original floor plan (including exact location of doors and windows) will help ensure that my suggestions could fit with the least amount of alteration to the existing structure and may also invite different suggestions from other HOUZZERS and happy to redraw your plans if you can correct this copy