The tradie also pleaded guilty to five further counts of possessing child sexual abuse material, which was recorded while he committed the other sexual offences.
He was hit with 14-and-a-half year prison term for the sickening offending.
But he appealed the length of the sentence because he pleaded guilty early and claimed his term was not properly discounted.
He was granted a 10 per cent sentence reduction for the plea, but argued it should have been 25 per cent.
The WA Supreme Court found his appeal to have solid grounds.
The criminal’s lawyer, Mark Gunning, said the original 10 per cent discount against his sentence was ‘manifestly inadequate’, adding his early plea had saved his daughter from testifying at a trial.
Public prosecutions lawyer Natalie Sinton argued against the reduction, noting the man’s daughter had given birth to his child and he had filmed his acts.
However, she conceded she was unaware of any case where an offender having entered a plea of guilty at the first reasonable opportunity was afforded a discount of only 10 per cent.
The Supreme Court panel of appeals ruled in the man’s favour, deciding the initial 10 per cent reduction had been ‘unreasonable’ and ‘plainly unjust’.
The panel adjusted his sentence to include a 22 per cent discount against the first three counts of offending, and 20 per cent for the remaining accounts.
The man’s sentence was set at 12 years, two-and-a-half years less than his original sentence.
‘As strong as the State’s case was in relation to all of the counts, counts one, two, and three were slightly weaker, having regard to the fact that they were not video recorded,’ the panel stated.
The court heard how the offending was ‘brazen’ and occurred on occasion with other children in the home, or on one occasion with other children in the room.