Complex sentence: Disney considered continuing the franchise in further films and a prime-time television series with Lizzie, Miranda and Gordo attending high school, which was to be broadcast on ABC, but the plans were never implemented due to contract disagreements with Duff's representatives.
Split into simpler sentences: Disney considered continuing the franchise in further films and a prime-time television series with Lizzie, Miranda and Gordo attending high school, which was to be broadcast on ABC. But the plans were never implemented due to contract disagreements with Duff's representatives.