A confirming library is simply a fasta format protein library with additional members of the family you are examining. For example, you may want to search with 12 representative glutathione transferases, but then confirm each hit against each of the 200+ known glutathione transferase homologs.
>gi|1169240|sp|P43387|DCMA_METS1 DICHLOROMETHANE DEHALOGENASE (DCM DEHALOGENASE) MSTKLRYLHHPASQPCRAVHQFMLENNIEFQEEIVDITTDINEQPEFRERYNPTGQVPILVDGDFTIWES AAIVYYLSEKYDCSSSWWGSTLEERGHIQQYMHWYAYTLRLGGGAFHWTIFAPMIYGYDKDFTVEVTKGR FLLYESFDILEKYWLKDGDYLCGNTLSYPDLATCQDLVSHDAGRIIPTSMWDSHPKVKAWFARMMDREHA KTVSAWQYENVRKYLDDGVKLNFQRKTAVLKGTEVYSGHNNGIIYNGDDDSFVTQHG >gi|118339|sp|P21161|DCMA_METSP DICHLOROMETHANE DEHALOGENASE (DCM DEHALOGENASE) MSPNPTNIHTGKTLRLLYHPASQPCRSAHQFMYEIDVPFEEEVVDISTDITERQEFRDKYNPTGQVPILV DGEFTVWESVAIARYVNEKFDGAGNWFGRGTQERAQINQFLQWYAYTLRLGGGAFHWNIFGCLIYGEKPY SPKFTAEQNKGRTLLYEAMGTLENYWLRDREYVCGDEVSYADLAAFHEFVSHEAGKIIPDRVWQGFPKIA AWFKKLSERPHAKTVSEWQYTNVGKIIRGELTASMFKRKTAVLKGTEVFSGHNHGIPYLNEKAEDYFKRV EKEGAAVA >gi|119164|sp|P12261|EF1G_ARTSA ELONGATION FACTOR 1-GAMMA (EF-1-GAMMA) MVAGKLYTYPENFRAFKALIAAQYSGAKLEIAKSFVFGETNKSDAFLKSFPLGKVPAFESADGHCIAESN AIAYYVANETLRGSSDLEKAQIIQWMTFADTEILPASCTWVFPVLGIMQFNKQATARAKEDIDKALQALD DHLLTRTYLVGERITLADIVVTCTLLHLYQHVLDEAFRKSYVNTNRWFITLINQKQVKAVIGDFKLCEKA GEFDPKKYAEFQAAIGSGEKKKTEKAPKAVKAKPEKKEVPKKEQEEPADAAEEALAAEPKSKDPFDEMPK GTFNMDDFKRFYSNNEETKSIPYFWEKFDKENYSIWYSEYKYQDELAKVYMSCNLITGMFQRIEKMRKQA FASVCVFGEDNDSSISGIWVWRGQDLAFKLSPDWQIDYESYDWKKLDPDAQETKDLVTQYFTWTGTDKQG RKFNQGKIFK >gi|1706588|sp|P54412|EF1G_CAEEL PROBABLE ELONGATION FACTOR 1-GAMMA (EF-1-GAMMA) MTGKLYGNKDNFRTQKVLIAAKLANKTVTLAGDAAPADKFPLGVTPAFEGDALLFGAESIGLHLTGTSAN AETVQWLQFAEGYLLPAVLGYVLPSVSAANFDKKTVEQYKNELNGQLQVLDRVLVKKTYLVGERLSLADV SVALDLLPAFQYVLDANARKSIVNVTRWFRTVVNQPAVKEVLGEVSLASSVAQFNQAKFTELSAKVAKSA PKAEKPKKEAKPAAAAAQPEDDEPKEEKSKDPFQDMPKGTFVLDNFKRSYSNEDTATKAIPHFWENFDAD NWSIWKCEYKYPEDLTLAFMSCNLINGMYQRLEKLKKNAFASMILFGTDNNSTISGIWVWKGDKLAFELS PDWQVDYESYTWTKLDAKSDATKKEVNEYLMWEGDFGGKKFNQGKIFK >gi|119165|sp|P26641|EF1G_HUMAN ELONGATION FACTOR 1-GAMMA (EF-1-GAMMA) MAAGTLYTYPENWRAFKALIAAQYSGAQVRVLSAPPHFHFGQTNRTPEFLRKFPAGKVPAFEGDDGFCVF ESNAIAYYVSNEELRGSTPEAAAQVVQWVSFADSDIVPPASTWVFPTLGIMHHNKQATENAKEEVRRILG LLDAYLKTRTFLVGERVTLADITVVCTLLWLYKQVLEPSFRQAFPNTNRWFLTCINQPQFRAVLGEVKLC EKMAQFDAKKFAETQPKKDTPRKEKGSREEKQKPQAERKEEKKAAAPAPEEEMDECEQALAAEPKAKDPF AHLPKSTFVLDEFKRKYSNEDTLSVALPYFWEHFDKDGWSLWYSEYRFPEELTQTFMSCNLITGMFQRLD KLRKNAFASVILFGTNNSSSISGVWVFRGQELAFPLSPDWQVDYESYTWRKLDPGSEETQTLVREYFSWE GAFQHVGKAFNQGKIFK
Clicking on the blast_pan PDF panel provides a page for re-searching the confirming database.
>gi|2506495|sp|P20136|GTM2_CHICK GLUTATHIONE S-TRANSFERASE 2 (GST-CL2) (GST CLASS-MU) (GSTM1-1) Length = 220 Score = 305 bits (772), Expect = 8e-83 Identities = 143/218 (65%), Positives = 167/218 (76%) Query: 1 MPMILGYWDIRGLAHAIRLLLEYTDSSYEEKKYTMGDAPDYDRSQWLNEKFKLGLDFPNL 60 M + LGYWDIRGLAHAIRLLLEYT++ Y+E++Y G APD+D S W NEK KLGLDFPNL Sbjct: 1 MVVTLGYWDIRGLAHAIRLLLEYTETPYQERRYKAGPAPDFDPSDWTNEKEKLGLDFPNL 60 Query: 61 PYLIDGAHKITQSNAILCYIARKHNLCGETEEEKIRVDILENQTMDNHMQLGMICYNPEF 120 PYLIDG K+TQSNAIL YIARKHN+CGETE EK RVD+LEN MD M +CY+P+F Sbjct: 61 PYLIDGDVKLTQSNAILRYIARKHNMCGETEVEKQRVDVLENHLMDLRMAFARLCYSPDF 120 Query: 121 EKLKPKYLEELPEKLKLYSEFLGKRPWFAGNKITFVDFLVYDVLDLHRIFEPKCLDAFPN 180 EKLKP YLE+LP KL+ S FLG R WF G+K+TFVDFL YDVLD R+F P C + N Sbjct: 121 EKLKPAYLEQLPGKLRQLSRFLGSRSWFVGDKLTFVDFLAYDVLDQQRMFVPDCPELQGN 180 Query: 181 LKDFISRFEGLEKISAYMKSSRFLPRPVFSKMAVWGNK 218 L F+ RFE LEKISAYM+S RF+ P+F A+W NK Sbjct: 181 LSQFLQRFEALEKISAYMRSGRFMKAPIFWYTALWNNK 218