* Piglet: While often portrayed as timid and easily frightened, Piglet can be quite manipulative when it comes to getting what he wants. He frequently uses his "weak" persona to gain sympathy and convince others to do things for him.
* Rabbit: Rabbit is known for his rigid, controlling nature. He often tries to dictate how things should be done and can become quite upset when his plans are disrupted. This control-freakish behavior could be seen as conniving, especially when he manipulates others to follow his rules.
Ultimately, the "most conniving" character is subjective and depends on your interpretation of their actions. It's worth noting that the Winnie the Pooh stories are meant to be lighthearted and whimsical, and the characters are generally well-intentioned, even when they exhibit less-than-perfect behavior.