How can I run 2" plumbing vents under windows in a 2x4 wall?
There is a reason why nearly all &quot;plumbing walls&quot; are located in the interior of the house, in a non-load-bearing wall. This is the reason.
You've got a bearing citrus tree, and you're talking about exterior 2x4 walls, so I'm going to assume that you're in the southern hemisphere in someplace with mild winters. That's relevant, because the applicable codes will likely be different.
Don't bother trying to tie all the vents together by going sideways in the the wall. Instead, tie the close ones together, and then try to get the rest together in the attic space. It looks like the tub and toilet vents could merge and go right in the photo. You might want to add another solid stud in the right-side gap right of the window, after installing the vertical vent.