Lisa then urged her followers to be kind to themselves and focus on the "sweet things" in life despite the ongoing pandemic.
"Be kind to yourself, stay grounded in reality and find simple sweet things to be grateful for everyday. Simply surviving as a human being right now is enough. More than enough. I am with you and surrounding you with love and healing energy," she wrote.
"Take some deep breaths and do something nice for yourself or someone you love. Tomorrow will be better X."
Lisa's sister Jess shared her own heartbreaking Instagram Story that could be in reference to Colleen's illness.
The singer reposted a tile that read: "You really never know how long you have on this earth and with these people you have with you. Live it. Love it. Love them. There is really no time at all to wait. Please, do it today."
In honour of International Women's Day in March this year, Jess also spoke about her mum's extremely rare neurological condition that was misdiagnosed on numerous occasions.
"Only 1300 Australian’s have ever been diagnosed. There is no cure, no treatment, and little to no research, support or funding to do with this disease. It presents itself in the most cruel & debilitating symptoms, losing all motor and cognitive function over the course of a few years. I won’t begin to tell you here what that looks like. It’s absolute hell," she wrote at the time.
Jess added that due to the lack of research and information available, they've had to live through the experience with limited knowledge of the disease.
"I will never have the words to explain how unbearable it is to see someone you love go through something like this," she wrote.
"The awareness of this disease comes second only to the note of strength my incredible Mummy has shown every step of the way. We are so blessed she is our mummy."
She added: "We don’t share the reality of this part of our lives. It's private, too confronting, too devastating and almost beyond our human capacity to process the daily grieving and energy required. We don’t share any photos or videos of what really goes on behind the smiling photos, but to those who know the reality of terminal illness, our hearts are with you."