They lost that challenge, but in taking the matter to the Court of Appeal they argued the plan breached the Reserves Act and that it didn't allow for enough public consultation.
The Court of Appeal's three judges backed the couple's arguments that not enough consultation had been done, saying the plan should have been publicly notified as required by the Resource Management Act.
"We have concluded that the application should have been publicly notified under s 95A of the RMA," they said in their recent decision.
"In the circumstances, the resource consent granted by the council must be set aside."
Earlier, the High Court had previously found the authority and Auckland Council both acted lawfully when granting consent to remove the trees on a non-notified basis.
The TMA had earlier been set up as a group to which ownership of Auckland's 14 tūpuna maunga (ancestral mountains) could be returned to 13 iwi.
The plan to revegetate Ōwairaka/Mt Albert maunga was linked to a wider plan to restore native flora, fauna, culture and mana to a landscape changed by colonisation.
The HTM group, many of whom had grown up in the area, have earlier told how they regularly walk the maunga and felt a deep connection to the towering oak and gum trees that had been in line for the chop.