Increasing the size of my mother

 At the moment I have been maintaining 180mg of 100% hydration starter in my fridge and baking a bread at a time a couple times a week using a Levain built from 90mg of my starter. I am thrilled with the state of my mother which is strong and rises predictably and has been producing incredible bread. It's really true that after it matures a few weeks it really takes off. I want to increase the size of my starter now so I am able to cook two loaves at a time while only having to double the amount I add to the mother so the additional feeding is more quickly converted into mother in the fridge. Over the next two days I plan to add an additional 50% to my mother so that I have enough to remove 180mg each time which would only equal 50%. Does this seem okay to everyone? I am reluctant to change anything too much since I am loving the results I get. As a test during my last baking I removed a couple tablespoons of starter and added them to 180mg of new food (90g flour/90g water). When this visibly doubled I removed 90mg and built my usual levain but its rise lagged far behind that of a levain I had started at the same time built from my original mother. I guess I am just looking for any kind of advice on increasing the size of your mother to be able to bake additional loaves. Also at refrigerator temps how long do you think a 50% feed would take to be converted entirely into new mother in the fridge? Thanks guys and a special thanks to Farinam whose guidance has brought many happily consumed breads to my friends and family these last weeks!