Actually, most went back to Germany just before the war as per Hitler's invitation.
Because I just woke up, I don't feel like translating, so here is Google translation:
Baltic German exodus from Latvian - 1939-1940th years has had a Baltic German exodus, the legal basis for the organization of 1939 was signed on 30 October Latvian-German agreement on the Baltic German exodus. As a result, in 1939-the 1940th In the winter of Australia left around 47-50000 Baltic, Latvian citizens (forced to emigrate Latvian lived and wrote in October 1939, the magazine "Leisure", 58,600 Baltic Germans). Baltic German political attraction of Germany as an officially set the goal for the first time publicly voiced on 6 October 1939, when Adolf Hitler Reichstag, inter alia, called Baltic Germans return to the Reich, to be precise - Door County (Reichsgau Wartheland - 1939 established between the province and Silesia Prussia German-occupied Polish territory which Germany is considered to be illegally deprived of the First World War as a result). It was announced that "Germans from Eastern Europe to return to the Reich under the auspices and participate in the conquered Polish rietumnovadu pārvācošanā". The first ten ships from Germany entered Riga 8, 9 and 10 October, but left the UK in October only the so-called valstsvācieši (Reichsdeutsche) - those who have German nationality had already pre-departure shares begins. Exit practical developments in the preparation and realization took the German Association of Latvian folk. It was organized and coordinated by issues such as: - where to, how, and what belongings packing of boxes you can buy or get for free, and that the time may help wrap up Dues property; who and how large bundles leads to the port for free and where you can order a free truck - with a horse or a car; where and what time to arrive for the sixth on board, etc Were created or involved in community organizations, such as the Cultural Service (Das Kulturamt) for baggage transportation issues - Transport Service (Transportbuero), yet other issues - National Care Service (Volkspflegeamt), hunters Union (Jaegerbund) German Women Association (Deutsches Frauenbund ), which took care of both the departure counseling issues (especially in large families, children, women etc., etc.) and on the clothing collection and distribution of the shares within the exit, and other organizations, which were expected to participate in the popular movements. German and Latvian press was launched massive propaganda campaign, the newspaper's publication is based on the idea of a unified German nation concept, trying to change the traditional Baltic German position, which is always yourself more an association with the Baltic cultural space rather than the German state and the public. On 9 October, the first time the Group's management statement, the newspaper "Rigasche Rundschau", said: "Among the Latvian and German Reich governments on repatriation agreement agreed in principle, which will be adjusted to the German people belonging to citizens of repatriation and related issues. Negotiations on this contract will begin during the next few days. "[1] It is important to exit propaganda including the Latvian Evangelical Lutheran Church Council of the Baltic German Chapter of the German Evangelical Lutheran bishop on 11 October 1939, issued a proclamation in which the exodus was declared" the inevitable requirement " . People's Group management is based on statements in the press used to form speech "German", "German", avoiding the term "Baltic German" (and even "Baltic German"). Similar changes in terminology also took place in the Latvian press. Press publications called for preparations: mostly packaging of certain items (such as valuable furniture), documents, proof of collection of different form completion and submission of the competent authorities. For those who did not want to abandon their homeland, the future of propaganda showed quite sad, "vācietība (Deutschtum) Latvian cease to exist. There will be no German schools, no German association, no association. There will be very little maybe exceptional person who remained here, that is, persons who are no longer the German people. Because the one who at that time separated from the group of his people, detached from his own people forever. "[2] Police officers visited all Baltic Germans census presented a recommendation to leave the UK because the stay is not desirable. A very small percentage of the Baltic Germans endured the moral pressure, but most came to terms with change and left the homeland.
Source: http://vesture.eu/index.php/V%C4%81cbaltie%C5%A1u_izce%C4%BCo%C5%A1ana
Contract for ethnic German Latvian citizens moved to Germany (vc. Vertrag Ueber die Umsiedlung Lettischer Buerger deutscher Volkszugehoerigkeit in das Deutsche Reich) - October 30, 1939, an agreement between the Latvian Republic and Germany on the Baltic German Latvian citizens forced departure from Latvian to Germany which was intended as a "one-off shares to the German folk group withdraws from the Latvian national unity." The implementation of the campaign was set aside for almost two months: emigrants after the surrender of Latvian citizenship and receipt of the document was up to 15 December 1939 to leave the UK. As a result, in 1939-the 1940th In the winter of Australia left around 47-50000 Baltic, Latvian citizens (forced to emigrate Latvian lived and wrote in October 1939, the magazine "Recreation" 62118 Baltic).
I don't know how much this helps, but the article lists these books in German:
Hehn J. v. Die Umsiedlung der baltischen Deutschen – das letzte Kapitel baltisch-deutscher Geschichte. 2. Auflage. - Marburg, 1984
Diktierte Option: Die Umsiedlung der Deutsch-Balten aus Estland und Lettland 1939–1941. / Loeber, D. A. (Hrsg.) - Neumünster, 1972
Bernsdorff H. Gesundheitsdienst Fürsorge wärend der deutschbaltischen Umsiedlung. // Baltische Hefte. 1970. Bd. 16.