While they were open to helping her in any emotional way they could, there were some practical issues that were harder to solve - such as finding the right swimwear.
Given Ruby, 12, loved swimming and the beach, the dad took matters into his own hands, creating and designing his own line of swimwear that helps to 'hide the bulge' so trans girls can feel more comfortable and confident.
Alexander, based in Toronto, teamed up with Ryerson University tech start up The DMZ, working with garment engineers to develop prototypes of a bikini bottom.
They developed the Ruby Shaping Bikini Bottom, which uses a mesh insert and a spandex fabric to lift and pull things into place.
After sending prototypes to trans kids in Canada, the US and Australia in 2019 to test out, he continued to approve the design before putting them up for sale through his company Rubies.
The line has expanded to include pink bikini bottoms, a one piece as well as T-shirts with the slogan 'Every girl deserves to shine'.
Each order also comes with a postcode with a personalised message from Ruby.
"Everything I saw was heavily branded just to trans people and had a quilted pad in the front. They didn't look like normal bikinis," he told TODAY.
"I wanted to create a garment that looks and feels like a regular bikini and a brand that resonates with kids, not just trans kids."
He is now also looking into creating cotton underwear that solves the same problem, another area he says needs addressing.
"I want to focus on the positive stories about these kids and normalise them," he said. "They're just kids. That's how people need to see them."
Reviews online from customers reveal just how much the products have helped trans kids around the world.
"These bottoms have taken all the Image anxiety away, finally my daughter can have fun with her siblings and friends at the pool and beach," wrote one parent.
"I'm so so grateful that you have created this fabulous product with our girls in mind. My daughter says they look and feel amazing. It was the confidence boost she needed."
"These bottoms are perfect for my daughter. We have struggled to find something for her to wear for swimming, and this is the ideal solution. She can now go swimming without fear of being stared at or judged," wrote another.