Ms Webb's memoriam reads: ''To my beautiful children, There is not a day that goes by that I don't miss your love, hugs and kisses, smiles, joy, laughter, and cheekiness.
''Always in my heart. Love, Mum. XXXXXX.''
She also thanked those who had supported her over the past year, especially her family, friends, colleagues, Women's Refuge, Victim Support and police.
''I don't know how I would have coped without you,'' she said.
The first anniversary comes ahead of a coroner's hearing into the deaths, which a Ministry of Justice spokesman said yesterday was scheduled to last four days and begin in Dunedin on April 21.
Devoted: Katharine Webb with Bradley and Ellen
St Leonards School principal Jo Wilson declined to comment yesterday, instead referring to a statement the school issued last month saying its teachers and pupils would remember the first anniversary in private.
In the statement, she said it had been a long and difficult year since the deaths of the siblings, who were pupils at the school.
''With the anniversary approaching, the school and community hope we will be able to acknowledge and remember them in private.
"As always, the St Leonards community is supportive of each other, but especially... Katharine and her family at this time, knowing the children will be part of our lives forever."