United Kingdom, Oct. 4 -- Chad Lowe's eldest daughter has shared a heartfelt tribute to her younger sister following her death this week.

Fiona Lowe passed away earlier this week and it later emerged the 13 year old had taken her own life, and now Mabel Lowe, 17, has pledged to "honour" her beloved sibling "forever" as she expressed her hope that the youngster has been able to find peace.

Sharing a number of throwback photos on Instagram, Mabel wrote: "I love you so much Fiona.

"I wish your short time here was easier and I hope your mind is at ease now. I will honour you forever and keep your memory alive. I love you, I hope you knew just how much."

Pretty Little Liars actor Chad, 58, and his wife Kim Painter - who are also parents to...