>>58415397
Lana's Mother having big titties is all due to one pre-episode release screencap .gif of Sarah and Harper pressing up against her chest, producing noticeable breasts. If I recall it's pretty the very first thing anyone ever saw of new anime Lana's Mother design. This is all it took to make her big mammaries, even when the episode actually released and she's flat as a board.

https://gelbooru.com/index.php?page=post&s=view&id=3663152
https://img4.gelbooru.com//images/19/c6/19c6195ddb30d8ec3e712fd4eaf318b8.gif

Also frankly Lana Mother's design vastly improves with breasts anyway, unironically and sex appeal aside.