I already have osteoporosis and take calcium with Vitamin D. But the "research" I did showed it is imperative to take Vitamin K with the Calcium and Vitamin D for the following reason:

"But vitamin D alone doesn’t dictate where the calcium you ingest ends up. Vitamin K integrates calcium into bones and teeth, preventing it from being deposited in soft tissues, such as the kidneys or arteries—important, since calcium deposits in the kidneys are linked with kidney diseases, and the buildup of calcium in blood vessels increases the risk of coronary artery disease, heart attacks, and stroke."

This are two websites but there are lots more out there saying the exact same thing if you want to research on your own: https://www.betternutrition.com/supplements/vitamins/why-you-need-to-take-vitamins-d-k-together/
https://us.betteryou.com/pages/vitamin-d-and-vitamin-k