After doing some further research, I think you're correct. A page on bfi's website states that Universal owns all of the pre-1948 Paramount titles.
One possible exception to this rule: prestonsturges.com states that Paramount is working on the DVD release of Preston Sturges' The Miracle of Morgan's Creek (1944/Paramount) which, by the rule, should be a Universal title.
Is all of that clear as mud??
I'll amend my post accordingly.
It would be GREAT to see "Ladies and Gentlemen, The Fabulous Stains" released to DVD now, following Diane Lane's Oscar nomination and all her recent publicity. Any update on the status of this cult favourite? If there is anyway you can make this happen... please do it. Thanks.