Not long after Full House had come to an end, Mary-Kate & Ashley Olsen returned, this time in a series of DTV mysteries that later migrated to the Family Channel (now ABC Family).
The Adventures of Mary-Kate & Ashley was a comedy-musical-mystery series that was meant for the little ones. The videos were readily available at the usual places, but today, are collecting dust somewhere, like the twins' later series. Fam, for that matter, gave up on the series after about a year, likely due to 1) low ratings and 2) Olsen fatigue hadn't dissipated yet.
Warner Video On Demand's YouTube channel provides a sample clip: