Id leave her, but place a lot of floating plants in the tank, even fake ones.
Then when she has the fry, they tend to hide up top among the floating plants, scoop them with a net and put them into a box.
Moving her to the box before she has them can cause her to abort them or reabsorb them. So best not move her.
But yes she looks pretty porky pregnant and given the box shape can be soon! Not all get the gravid spot, especially among the fancy coloured mollies.