Nothing in this non-trade with LA/IND would enable Dallas to trade any more of their own picks than they can right now. It only offers the Mavs a provisional Boston pick that is likely to convey, but not guaranteed.
Also the Stepien Rule (and the workarounds) are being misstated in the conversation. The earliest contingent pick the Mavs could offer of their own would be TWO YEARS after the Stepien limit is satisfied, not the following year. That is, if trading a Mavs' pick before NY is designated to get the Mavs pick in 2023, the pick being conveyed to Team X would have to be stated as "two years after FRP conveys to NY" so no sooner than 2025 and might be as late as 2027. Having, or not having, a provisional BOS 2023 pick would not change that limit, as the trade wording must account for any and every B2B non-1st scenario.
Also the Stepien Rule (and the workarounds) are being misstated in the conversation. The earliest contingent pick the Mavs could offer of their own would be TWO YEARS after the Stepien limit is satisfied, not the following year. That is, if trading a Mavs' pick before NY is designated to get the Mavs pick in 2023, the pick being conveyed to Team X would have to be stated as "two years after FRP conveys to NY" so no sooner than 2025 and might be as late as 2027. Having, or not having, a provisional BOS 2023 pick would not change that limit, as the trade wording must account for any and every B2B non-1st scenario.