The Definitive Guide to Data Quality
You can alias the lookup table. We had a requirement where columns c1,c2,c3,c4,c5 and c6 of table A have references on column p of Lookup table L i.e. Multiple columns from table A have references to single column in lookup table L.
We achieved by alisaing the lookup table 6 times and connecting all the aliases and the source to tmap and it worked fine without any issues.