Both Stolyarenko (closer transliteation to original surname, equivalent to CARPENTER in English) and Tatarko (means SMALL - reference to stature - TARTAR) can be found in both Kharkiv, the regional capital, and in the county seat Lozova (population appx 70,000). There is also a village called Lozova in Borivskij raion/county > Kharkivska oblast/region ? Was the family from a fair size railroad town or from a rural village in Borivskij raion/county > Kharkiv region? ? Stolyarenko is by far the more common surname.
The surname Tatarko indicates some influence of micro-ethnic Tartar group in bloodline. Google UKRAINIAN TARTAR and you will find loads of info.
I doubt that the family volunteered as Ostarbeiter /Forced Laborers, unless they did it early on in WW2??? I suspect that they were forcefully taken by the Nazis. This is not written in stone. I am only guessing.
The Germans kept meticulous records of anyone, who stepped foot in their country. You can obtain the entire family history in Germany during and post war by making an inquiry at Bad Arolsen Archives. These archives will provide you w/details of exact experience in Germany and other personal details like EXACT place of origin, names of parents, etc. Inquiry by immediate family is available for free. Make the inquiry in Mother-in-law's name. All you need to provide is her parents' full names and any other spelling variants, and their exact birth dates, or as exact as she has it. Do not provide more info than that !!! You want them to locate any and all records possible.
Your inquiry can be done by e-mail. I understand the archives has upgraded their service and response can be received via e-mail as well. Response can take as
little as three days or as much as three months.
Upon accessing site click HUMANITARIAN REQUESTS. Follow instructions.http://www.its-arolsen.org/en/homepage/index.html
Displaced Persons' (DP) Camps Post WW2http://www.dpcamps.org/
Whenever doing this kind of research, you really want to retrace the exact steps back. So Germany first and then you will move your research to Kharkivska oblast > Ukraine.
I did find appx 20 Stolyarenko and 14 Tatarko in Lozova, the county seat. BUT I am sure Olena does not want to acquire family that might not be her own, so everything has to be done to ascertain as much info as possible.
When you get a response, feel free to e-mail me and then I can point you to the next step of your research.