Expenses can be tracked in two places in Sisu:
Admin > Expenses
Admin > Lead Sources
Additionally, they are not connected. This video explains this more:
Video Note: To optimize viewing, watch this video on Loom. You can do this by clicking the square icon with an arrow coming out of it, which appears in the top-right corner of the video.
Also, for Admin > Expenses, this video specifically explains how the Categories and Recipients get added: