Both of those models were produced during the Star League era, so you can guarantee a fair share of them would have found their way into Steiner hands even well before the marriage of Melissa Steiner and Hans Davion.
The Victor is a popular commander's mech, (Hans Davion's friend Arden Sortek piloted one almost exclusively, despite having at least one shot out from under him) so you can be sure that after the establishment of the FedCom, a fair few deals were made by Steiner's Ducal Generals to get their hands on some from the Davions, who were producing them at the time. Though, a regular complaint by Steiner forces during the reign of Hans and Victor were that they did not receive the war material that they wanted/needed/deserved from the Davions. In terms of lore, you might have to point out how much the thing cost you to wrench it from the grip of one of the FedRats.
As for the Jagermech, it's a pretty popular ballistics platform (even in canon) and you know the Steiners love their autocannons, almost as much as the Davions.
So, in short, sure, a Victor and a Jagermech within the Steiner lines wouldn't raise any eyebrows, except maybe by other Steiner commanders wondering why you aren't in your Steiner-issue Atlas.
Edited by Eleck, 08 September 2013 - 06:42 AM.