I don't think thate going to be a thing. you could alternate between sus imm and sus soft articulations, or simply layer one of the short articulations. That said, turning off legato and just playing with the sustain patch feels correct enough most of the time.
(1) staccato articulation in lower velocities could work as a more agile detache.
(2) portato short works as a longer detache, but the release tails don't seem to be scripted to allow you to choose when to release, so you can't really control the detache note length.
(3) sustain you can control the detache length, I totally agree with ProfoundSilence's suggestion - also, sometimes it helps to use a gradual, consistent upwards increase in CC1 control until you release, that doesn't always work, but can be the desired effect sometimes.
As a side note - I'm hoping the release trails might become one of the advantages with the sine player. Based on the trailers and NAMM videos about sine player, it seems like intelligent loudness matching to make release trails more seamless is one of the features.
also, don't forget that other sustain-ish articulations exist.
One of my favorite patches is the expressivo… that and the decrescendo , layered with another short of some kind if needed. often times I like to have expressivo on a multi so I can put legato on and off, and I often play unison, with one legato and one not. This helps keep a good mixture of blur and connectivity.
below is a short example using the melody from @OrchestralTools Sascha Knorr's catchy BWW demo.
I used a single midi performance and pasted it through the octaves, using the expressivo's crossfaded in a multi, both violins having legato activated and the viola and celli without. I occasionally layered spiccato at low velocity - and in one particular case I used a portato layered. wasn't rocket science - just picked what made sense for that phrase to have a little more bump.
Thank you for your replies Yes I found also that some sort of spiccato and staccato patches might fit the detaché way of playing. I found also that the BS "Vln 1 Spiccato" & "Spiccato exposed" - besides other ones as some useful patches here. In the example below I use stacc. and spicc. for detaché playing. In my little arr. of the - Einzug der Königin von Saba ~ Arrival of the Queen of Sheba ~ by Georg Friedrich Händel. The first chair of the BS Ext. "D" has of course some more chamber limited size sound here.