Using the JOSM editor you could draw the whole block outline then terrace the block into eight even houses. JOSM takes longer, more effort to learn but is a much superior editor, recommended if you're going to do much OSM editing.

Hi, I see you are using the iD editor. For your five new buildings, you first need to join the corners of the buildings. Select/highlight one building, drag a corner node onto the corner node of the adjacent building, release it, it should stick/join the two corner nodes together, (test by again dragging the joined node, it should drag the corners of both buildings. Repeat for all corners to be joined.

Once the corners are joined you can square up the five house block. The houses have to be fairly square to start wih. While holding down the Shift and Ctrl keys, left click the mouse on each house to highlight/select all of them, release the Shift and Ctrl keys, all houses should remain selected. Now hover the curser over one of the outlines, right click the mouse, click the square icon, (forth one down). They should all square up.

Regards Bernard.

Hi, Welcome to OpenStreetMap.

I've tweaked the buildings to square them up, last tweaked the postal codes.

Regards Bernard.

Hi, Welcome to OpenStreetMap.

You requested a review of your two changesets. I've noted the date and thus reverted the changes. Please note that with the amount of warnings given above it was not very convincing and would have disrupted routing. How did you think the trains would have negotiated the 90 degree turn off of the main line?

Regards Bernard.

You've made duplicated highways in nearly all your changesets. Please read the help pages and OSM guidelines before more mapping.

Duplicated highways seriously disrupt routing.

Duplicated highway removed.

Duplicated highway removed.

Duplicated highway removed.

Duplicate highway removed.

Duplicated highways removed.

Hi, Welcome to OpenStreetMap.

I've reverted this changeset because the way added duplicates an existing highway which will disrupt routing.

Regards Bernard.

Even more duplicated highways removed, I think that all.

Hi, Several highways are duplicates of existing highways which disrupt routing.

I've removed the duplications.

Regards Bernard.

Other duplicated highway removed.

Hi, Review, both highways are duplicates of existing highways which disrupt routing.

I've removed the duplications.

Regards Bernard.

Hi, Welcome to OpenStreetMap.

You tagged the outline of a residential area as a highway, this causes disruption to routing. I've made corrections.

Before uploading please heed any warnings like those given above.

Regards Bernard.

Duplicated university deleted, grounds alreaddy mapped. House tagged correctly.

Duplication, changeset reverted.

Duplication, changeset reverted.

Hi, This changeset has been reverted because it only adds duplicated highways and fictional names. Please don't add your personal routes/features/notes to the OSM database as it disrupts routing.

You're welcome to add genuine, on-the-ground, and verifiable features as per OSM best practice and guidelines.

Regards Bernard.