For reference-
Mack Alice Gilbert of 4 Eglantine Gardens Belfast spinster died 12 June 1948 at 39 Malone Road Belfast Probate Belfast 17 December to Hubert George Montgomery Mack and Cyril Hugh Mack company directors. Effects £5065 6s. 4d.
Looks like Emma might have moved?
Mack, Emma Laura of 71 Eglantine Avenue Belfast spinster died 20 January 1963 Probate Belfast 26 April to Cyril Hugh Mack merchant. Effects £4598 16s.
Probate of the Will of Hugh Mack late of Dalboyne, Lisburn, Co. Antrim, Knight, who died 11 September 1920 granted at Belfast 7 February 1921 to David Mack, 55 Eglantine Avenue, Belfast, James Mack, Parkmount, Lisburn and Hubert Mack, Dalboyne, Lisburn, all Warehousemen. Effects: £22,717 6s 0d.
Mack, David of 55 Eglantine Avenue and of 3 Windsor Avenue North and of 19/21 Donegall Street all in Belfast company director died 3 March 1959 at Musgrave Clinic Royal Victoria Hospital Belfast Probate Belfast 6 January to Cyril Hugh Mack company director. Effects £16427 19s. 2d.