The good news about turning a window into a door assuming it s wide enough is that the advanced carpentry required for altering a load bearing wall.
How to turn windows into french doors.
Build a wall support structure to create excellent support framing especially if the wall is load bearing.
For example say you have a finished opening size of 72x80 then buy two sets of doors that are 36x80 and install them side by side according to the instructions.
Install two or three additional doors that don t open or close to replace the wall itself.
You will need to cut two different lengths of strips for each window.
Remove the hinges and knob from the door.
Eventually may put screen door from deck onto screened porch but for now a door to the far left gives access to deck and steps into back yard.
Unscrew and remove the track and any other hardware that was supporting the door inside the closet.
Here is a recent response on cost to install a sliding glass door which is quite a bit easier than a french door but same general size.
How to turn a bi fold door into french doors.
Take your bi fold door out of the closet and off the track if it isn t already.
So you ve just built a new deck on the back of your house and those once lovely double windows in the living room would now make a better door sliding glass or french out to that awesome deck.
Because you are almost certainly going to be increasing the width of the opening and very likely raising and lengthening the support header over the window as well you are going to to be above the cost in the referenced comments probably in the 2000.
Remove the single standard door and install a french door wall by using one of the french doors normally to enter and exit the room.
Converting an existing window into a door opening with bi fold french doors is something that will take preparation and time to do but the end result will be fabulous.