I love The Parent Trap Movies 1 and 2

I enjoyed watching the Parent Trap movies with my girls..I have them all But I would love to have the 1989 version of Part 3 with the triplets. How can I get the copy on DVD. Please help.. Ive been trying to find it for several years. I really really want a copy to enjoy with my granddaughters. Thank you for this web page... Ms. Jean