No one has the right to select a partner for you.

When selecting a partner, he/she must be legal to play against both the player challenged and his partner. However, the challenged player’s only obligation is to select a partner who can play the challenger.

You cannot refuse a challenge because your regular or favorite partner is unavailable. Once challenged you must immediately set a table and select an available Case's Ladder player as your partner.

You cannot refuse a challenge in order to partner with another. You must each field challenges separately when more then one challenge exists. When each has been challenged, he/she cannot accept the SAME challenger under the pretense of highest rank in order to continue partnering.

You cannot refuse a challenge to partner another because the game would be an "up" for you by partnering.