https://wizdomz.wiki/wiki/Usin....g_a_Cat_Flap_in_Bifo
Cat flaps allow your pet to come and go whenever it wants. You can choose a locking flap to keep other cats and animals from entering your home. Installing a cat flap on the bifolding door is feasible as long as the door frame is made from toughened glass. The frame should not be damaged or rotten. The procedure is similar to installing one on a wooden door or uPVC. Easy to install A cat flap added to your bifold doors will allow your pet to go inside and out of your home freely, without having to open and close the door manual