If 2 or more defendants are alleged to be jointly, or jointly and severally, liable to the plaintiff in respect of a debt or damages and a right of contribution or indemnity is alleged to exist between the defendants, the consequences as to costs referred to in rule 289 do not apply to an offer of compromise unless –

(a) in the case of an offer made by the plaintiff, the offer is made to all the defendants and is an offer of compromise of the claim against them all; or

(b) in the case of an offer made to the plaintiff –

(i) the offer is to compromise the claim against all defendants; and

(ii) if the offer is made by 2 or more defendants, by the terms of the offer the defendants making the offer are jointly and severally liable to the plaintiff for the whole amount of the offer.