It was so nice to hear from a TX Keilberg -- you are the only one to contact us so far! My gm was Augusta Emma Keilberg [b.1880 Germany - d. 1950 WI]; her parents were Wilhelm Ernst Keilberg [b. 1844 Burgstadt, Saxony d. 1917 WI] and Emma Augusta Franke [b.1846 Germany - d.1936 WI]. Wilhelm's father was possibly Friedrich or Christian Friedrich Keilberg.
Keilberg seems to be a scarce name in the entire US. As far as we know, ours in WI are related to any who lived in PA and in Chicago, IL.
The only others we have found are in TX. Looking at the earliest online stuff we could find, with 1st names Otto and Louis, a connection seems likely, but...I guess we need facts that actually, directly connect. Several TX Keilberg links I have tried are no longer operating, from searchable charts submitted to either Ancestry, LDS FamilySearch or Rootsweb. Have you had any response from them?
I also subscribed to some TX County and Germans-in-TX Rootsweb mailing lists for a while, very interesting and helpful.
A summary of our Keilbergs is on my sister Tracy's website, which I will send to you in my next message. Which TX Counties did your Keilbergs live in? We would be happy to exchange further information.