I find it too contrived that Leandros sister would be interested in what shoes Joanna was wearing and would search the house to confirm this...its all manufactured evidence
I find it a bit odd as well. It doesn't seem to be mentioned in Leandro's statement, so there doesn't seem to be any corroboration. The sister's statement doesn't say what colour these shoes were, so I'm not sure where that detail is supposed to have come from.
Several statements say that Joana had been to stay at Leandro's mother's house for a few days (and there was a birthday party on the Sunday). Joana and Leonor got home at around 18:00. Joana might well have been wearing shoes for the party and changed later.
From Leandro's statement:
A CC estava desde 5ª feira anterior na casa da mãe da testemunha. A arguida BB no domingo foi também à casa da mãe da testemunha, a uma festa de anos, tendo regressado com a CC à Figueira por volta das 18h.ETA: Correction - she had stayed at Leandro's mother's house, it didn't say "parents'".