I asked someone this the other day and they were like well it's leading to Shona realising Jodie is weird. ... ooookay but that doesn't impact anything? If Jodie was involved in a high-stakes way, like (to borrow a bunch of soap storylines) going to be a surrogate for Shona and David, or about to marry a close friend of theirs, or about to adopt a child, or be David's new boss or something, then her being a weirdo would have a tangible effect.
"Sister I haven't seen for years turns out to be a bit weird" is a nothingburger.