The only thing i could find on "Tec3" was that it could be either T3 codeine tabs or percocet (oxycodone) depending on the imprint. I suggest you find out exactly what pills you have before continuing, just look at the imprints and type them into google.
Either way codeine, oxycodone, and ativan are all CNS depressants and if you take them together without a tolerance you have a greater chance of adverse effects. It's better if you just take them on their own.