None of the provisions of Sections 81-7-1, 81-7-3, 81-7-7 and 81-7-9 of this chapter shall be mandatory on branch banks heretofore established and in operation on April 2, 1934, nor on the parent bank of such branch banks so far as such branch banks are concerned, but such parent and branch banks shall continue to operate under the laws in effect immediately preceding the enactment of this chapter, so far as such branch banks already established are concerned. However, when any parent bank now in existence shall hereafter establish a branch bank, it shall so far as such branch banks hereafter established are concerned, comply with this chapter in all respects.