OOC: Let's try and put the tactics together outside of RP, just to speed things along. I propose Heinrich and Maia go on the roof at J6 and J7, standing at the edge where they can be seen from the alley but not from the sidestreets (where they might attract unwanted attention). They pull the ladder up after them, and lay it on the roof by J13 (for reasons I will explain in a minute).
Shayuri, if you want, Garnet will give Maia the +1 longspear. If anyone does come onto the roof to melee, or try, or if there's a flying attacker, a reach weapon would be useful. But if it's out of character for her to take it, or some reason it's a bad idea, feel free to pass.
We put everyone else on the ground just inside the alley, near K/L 12/13, perhaps spreading them out just a bit. We retain control of 1 end of the alley so we don't get boxed in. Also, with the ladder at that end of the roof, Heinrich and Maia would have an easier time getting to ground near the group if they need to get off the roof quickly. They would also have the option of coming out on the street rather than the alley.
Seem reasonable?