Absolutely you can, and I often recommend that women use both. Both vaginal estrogen creams--like Estrace--and vaginal moisturizers--like Replens--are typically used twice a week. Because each needs to be absorbed and, frankly, because it might otherwise be a little messy, I recommend that you alternate application. You might, for example, use the Estrace on Monday and Thursday and the Replens on Tuesday and Friday.
Glad you're taking care of yourself!