Joi validate at least one of 2 input fields are completed

I seem to hit a roadblock when it comes to joi's .or() function as it doesn't seem to implement as I'd expect.

I have 2 text input fields, both have their own way of validating, though only at least one is required.

    const schema = joi
      .object({
        "either-this-field": joi.string().trim().max(26),
        "or-this-field": joi
          .string()
          .trim()
          .regex(/^\d+$/)
          .max(26)
        "other-field-1": joi.string().required(),
        "other-field-2": joi.string().max(40).required(),
    
      })
      .or("either-this-field", "or-this-field");

it just seems that this or doesn't do as I'd expect and each field from the or is just validated as per it's own validation rules

if neither field has values, then I'll display error for both fields until at least one is completed

from Joi validate at least one of 2 input fields are completed