What do you mean by harder and shaped liners? The baggie versus the "cupped" liners? Yes, you can. Also, store brands might appear harder, they are fine to use... and in many cases, even better. I have used both the bag-like types liners and the formed liners, and prefer the formed liners. Never had a leaking problem. You just have to be careful when pushing air out of the bottle, don't push too quickly or the formed liner might fall out of place. My mom had this problem many times and prefers the baggie ones.
at 11:38 PM on May. 21, 2009