Map Type won't support append method

append(ri!selectedCards, save!value)

This code above is getting the following error:

Interface Definition: Expression evaluation error [evaluation ID = 788c2:8d9d9] : An error occurred while executing a save: Expression evaluation error at function 'append' [line 99]: Insert is not supported for Map types

- ri!selectedCards' type is Map Type like local!options

- fv!item comes from a loop through local!options:

  local!options: {
    a!map(
      id: 1,
      icon: "home",
      name: "House",
      desc: "A single family home, townhouse, or duplex"
    ),
    a!map(
      id: 2,
      icon: "building",
      name: "Condo",
      desc: "A multi-family building in which you own a unit"
    ),
    a!map(
      id: 3,
      icon: "coins",
      name: "Coin",
      desc: "A coin icon to appear"
    )
  },

- save!value is the same as fv!item

link: a!dynamicLink(
  value: fv!item,
  saveInto: a!save(
    ri!selectedCards,
    if(
      ri!allowMultiple,
      if(
        contains(
          tointeger(ri!selectedCards.id),
          tointeger(save!value.id)
        ),
        difference(
          ri!selectedCards,
          { save!value }
        ),
        
        append(ri!selectedCards, save!value)
        
      ),
      save!value
    )
  )
),

How could I deal with this error on a scenario I want to allow multiple selections if I cannot append? The fun part is that the difference method is working with no problems at all