How to stiff starch some dollies to frame or just display?

My grand mother was soaking them in sugar and water and ironing them.

I thought I heard somewhere you could use starch

Sugar starch.

https://www.geniuskitchen.com/recipe/doily-sugar-starch-342748

https://homeguides.sfgate.com/stiffen-table-doilies-53633.html

Or you could use commercial liquid starch or spray starch. I would stay away from those as they could discolor the doilies or disintegrate the fibers over time.

My aunt used to have a board with many nails in a circles. She would use the sugar water starch and then "pin" them to this board and let them dry. You could use a piece of card board and pushpins instead! You can also use a corn starch mixture: Heat 2 cups of water to boiling, now mix 1/2 cup cornstarch with 1 cup cold water and have another cup of water available. When the water is boiling, add cornstarch mixture slowly, stirring constantly. If mixture becomes too thick (which can happen quickly), add some of the extra water. After if cools, saturate the items to be starched, squeeze out excess, shape and let dry. Press with steam iron. Leftover starch may be stored in refrigerator for use at another time. If it separates, use a wire whisk to blend it.

Here's some info for you! http://www.textilefusion.com/how-to-starch-a-doily/