Yes; targets can be added later, but through an annex signed by both sides rather than imposed unilaterally. Under the Turkish Code of Obligations (No. 6098) changing the essential terms of an existing contract depends on the agreement of the parties, so targets and sanctions loaded onto a distributor without its consent may not bind it at all.
In practice the soundest route is an annual target protocol: the measurement rules, the reference period, what partial achievement means and the consequences tied to the target — loss of discount, a review of exclusivity — all written out plainly. To reduce resistance it helps to package targets into the contract renewal periods and to define them in terms that are both achievable and measurable. Where termination is to be tied to the target, setting that out alongside a staged warning process makes it far easier to prove later.
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