I don't know if this is obvious but just in case
a) you can contact the parish and ask for the info you want (parents, siblings, etc)
b) you can go to a place where you can access microfilms to find out the same.
c) you can hire a researcher in Finland (with access to the microfilms and or parish records)
d) you can try to find some to volunteer to do the research in Finland
(a) is best because it might be that the "moved-out" list is the easiest way to find Tekla and 1907 might not yet be microfilmed/available due to privacy.
Please note that getting to the "Hiski-period" doesn't mean that you should use that as your only source. If you want to do Finnish research, you will have to be looking at the microfilms at some stage. Or wait until someone has had time&motivation to digitize the records to www.digiarkisto.org
BTW, there is to "Turku-Pori". Turun ja Porin lääni - a now historical entity - is probably meant.
Lehtimäki is not a very unusual name so it might be that the shop keepers with that name currently in Siikainen are of no relation. But if you want to send them a letter just in case the address is on page http://www.tarmo.net/index.php?page=shops&action=show&am...