Well Joan, I finally had success in locating Ellie!
I did an Ancestry.ca search an hour'ish ago and spotted a Nellie Sayle in the Canadian Passenger Lists. I didn't have a Canadian membership in Ancestry, so I couldn't see the details. Cheaply subscribed, looked at the details and saw "Nellie" traveled from Liverpool to Montreal on the Grampian in 1919 with a destination of Edmonton to "join her father". Yippee! That's Ellie Isabella Sayle, my half-sister!!!
Finding her took me about 3 years... Whew! Now to see if I can find an Albertan marriage for her!!!
I thought she may have come to Canada much later and even thought she may have married in the UK but I was wrong... Nice feeling to get her to Canada and getting together with her father when she was just 15!