Welcome TLee. Where to start? First and foremost there are two Elizabeth Chadwicks. One is from the US and writes romance novels. You can pretty much figure out who is who by the title and cover. The ones that I feel need to be read in order are The Greatest Knight and then The Scarlet Lion and also her Ravenstow Trilogy - The Wild Hunt, The Running Vixen and The Leopard Unleashed. The Ravenstow trilogy are the first three written and while very good aren't as good as the newer stuff, although they are being rewritten and republished.
Some have related characters and families, i.e. Shadows & Strongholds/Lords of the White Castle and The Winter Mantle/Falcons of Montabard but they are stand alones -- you're not going to miss anything but reading them out of order.
They are getting hard to find in the US (even used) and a bit spendy. They can be ordered from the UK and Canada. The Book Depository has free shipping or some books stores in Canada do sell them. I've seen them listed on Abebooks as well, they have US sellers who import them and then while you pay shipping you don't pay the credit card exchange fees and exchange rate.
a list of her books that might help you out.