I have a herder

Bella was said to be a Shih Tzu at the shelter. I disagree with them but anyway when I let the dogs outside in the morning Molly pees and poops on command so she done real soon. Bella never learned that so sometimes it her takes awhile. I am out there to watch. After Bellas done she comes up the stair to go inside to get her treat. Molly on the other hand gets done first but loves to be outside so she is not ready to come inside even for a treat. Recall - Mollys is good in the house not so much outside. But she just turned 2 years old on the 16th and has never been outside off leash until this year so we have to work on that. Bellas recall is the greatest. She is also 2 years old. We got her about a month and 1/2 ago from a shelter and the only things she knew was her name and that no meant stop doing what you are doing. We have taught her to sit and to take treat nice so far we are working on walking on leash right now. I know I`m starting to babble on so one day Molly with her no recall outside I told Bella to go get Molly and she did. She got behind Molly and made her come up on the deck to come into the house. We have asked Bella to go get Molly many time after that and she does go get Molly and have her come up on the deck to come in the house. Bella may not herd anything else but she does herd Molly. For the treat that she knows she is going to get????? I Don`t know.