Nola,
you best bet would probably be to trace the passenger lists of those who emigrated to Patagonia. They are to a large extent freely avaiable.
The msg below was posted on another board at the weekend. Perhaps this can give you a bit of a start. There are no Evans listed here, but there might well be on the full list, or on passenger lists from other ships:
Subject: Emigrants to Patagonia
I saw this reference on another list relating to emigration to Patagonia who emigrated around 1900 with a large group from the Caernarfon area.
I thought you might like to see some of the names of various families from our general area of interest who left on the Ship Mimosa in 1865:
courtesy of Jeremy Howat at:
http://www.immigrantships.net/v3/1800v3/mimosa18650728.htmlImmigrant Ships Transcribers Guild
Ship Mimosa
Liverpool, England to Patagonia, Argentina
28 July 1865
12 DAVIES Robert 40 Llandrillo
13 DAVIES Catherine 38 Llandrillo
14 DAVIES William 8 Llandrillo
15 DAVIES Henry 7 Llandrillo
16 DAVIES John 1 Llandrillo
48 HUGHES Griffith 36 Rhosllaner-chrugog, G.C.
49 HUGHES Mary 36 Rhosllaner-chrugog, G.C.
50 HUGHES Jane 11 Rhosllaner-chrugog, G.C.
51 HUGHES Griffith 9 Rhosllaner-chrugog, G.C.
52 HUGHES David 6 Rhosllaner-chrugog, G.C.
53 HUGHES John 30 Rhosllaner-chrugog, G.C.
54 HUGHES Elizabeth 39 Rhosllaner-chrugog, G.C.
55 HUGHES William John 10 Rhosllaner-chrugog, G.C.
56 HUGHES Myfanwy Mary 4 Rhosllaner-chrugog, G.C.
57 HUGHES John Samuel 2 Rhosllaner-chrugog, G.C.
58 HUGHES Henry 1 Rhosllaner-chrugog, G.C.
107 JONES William R. 31 Bala
108 JONES Catherine(Bedol) 31 Bala
109 JONES Mary Ann 4 Bala
110 JONES Jane 1 Bala
123 PRICE Griffith 27 Ffestiniog
125 RHYS James Berry 23 Ffestiniog
131 ROBERTS John Moelwyn 20 Ffestiniog
132 ROBERTS John 27 Ffestiniog
133 ROBERTS Mary 27 Ffestiniog
134 ROBERTS Mary * Ffestiniog
135 ROBERTS Thomas 2 Ffestiniog
136 ROBERTS John infant Ffestiniog
- and many others from Liverpool, Birkenhead, Bangor, Aberystwyth,
- 164 in all.