Scott Hall & Kevin Nash were not two ham & eggers - they were two of the biggest stars in the industry & two of the top five stars in the WWF. Vince McMahon didn't invest all that TV & money, marketing & merchandising, Diesel & Razor Ramon, to simply decide he didn't want them.
The final appearances of Diesel & Razor Ramon in the WWF occurred at MSG & it was the first indoor non-PPV house in WWF history to top $300,000 (specifically $319,411) the biggest drawing non PPV MSG live event from 1990 to 1997 drawing 18,800 (16,564 paid), & the second straight MSG sellout which was the first time that had happened in 11 years. Diesel headlined the event & Razor Ramon was in the semi-main. In true Vince McMahon fashion he was gutted they were leaving but didn't sell it.
Vince McMahon later admitted in hindsight had he known the impact Kevin Nash & Scott Hall would have on the WWF vs. WCW battle, he would've offered them enough money to keep them.
Scott Hall were offered "Sting money" which was around $750,000 GUARANTEED for around 180 days when he was only making around $400,000 not guaranteed for working double the days in WWF. Sports agent Barry Bloom negotiated a favoured nations clause meaning Scott Hall gave a list of 10 of the top names in the industry & if WCW signed them to bigger contracts than what he was getting he'd instantly get bumped up to the say pay. Barry Bloom then negotiated the deal for Kevin Nash at a higher rate automatically elevating Hall to the same level as Nash.
When Hall & Nash came to terms with WCW, Turner Legal signed them to what they called "Deal Memos", which are promissory notes saying that these are the terms that have been agreed to and these pieces of paper say they have to at some point sign a contract agreeing to these terms. Deal memos are legal working agreements, but that didn't mean that Hall and Nash couldn't show up on WWF television if they wanted to. That's why WCW panicked when they saw a Jim Ross cut a promo about bringing back "Razor and Diesel". The Turner money people freaked out, and flew Hall and Nash out to Atlanta to have them sign official contracts plus an extra $400,000 making them exclusive to WCW.
In regards to merchandise because WCW didn't have the infrastructure to calculate royalties, they would just Hall & Nash an extra $400,000 on top of their original contracts.
When WCW signed Bret Hart to a huge approx. $3 million per year contract , both Hall & Nash agreed to waive their favour nations clauses but they still got an extra bump in pay.
Kevin Nash also got an extra $500,000 when they asked him to become WCW head booker.