In Cypress I can't select a dropdown value because value not loaded first time and awaits for another dropdown value to be loaded

In my Cypress test I want to select one value from a dropdown list but I have to wait random time to have this value loaded in this dropdown (this one is populated when another and previous dropdown value is selected)

I tried many things like :

• cy.click use on the parent element of the "select" with timeouts but ko
• cy.select use with timeout and force click options but ko too
• cy.request to wait for the WS responses but makes the code unnecessarily complex and doesn't work too
• the best try I have currently is this one :

cy.get('select[id="form_chantier:ste-menu"]')
        .should(($optionsArray) => {
          expect($optionsArray.get(0)).to.have.property('childElementCount', 172)
        })
        .then(() => {
          cy.get('select[id="form_chantier:ste-menu"]').select('01 SNEF')
        })

cy.get('select[id="form_chantier:sce-menu"]')
        .should(($optionsArray) => {
          expect($optionsArray.get(0)).to.have.property('childElementCount', 252)
        })
        .then(() => {
          cy.get('select[id="form_chantier:sce-menu"]').select('01 SIEGE')
        })

It works for the first select but the second it's ko because when the first dropdown value is selected the seconde dropdown values data are not loaded fast. How can I solve this problem please ?