There's no way to tell without having a pedigree. Or if you have the registered names of the parents. Also, with a BYB your dog is likely a mix of several lines and BYB dogs with no intent behind it. Looks are very deceiving, and there is no way to tell lines based on looks. Lines are about a lot more than looks, they are temperment and drive and work intent and they are protected by responsible breeders. Just enjoy your dog.
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MacKenzie - Workling Line Female (In Loving Memory)
Wolfram - West German Showline Male [SG1, CGC, DDN, CN, EN, IN, VN]
Bash - Working Line Puppy