How do we put in place an attache in a diplomatic or consular offfice? What are the legal bases?

Question

justifications for putting an attache in a diplomatic or consular offices or embassy, be a police attache, fire attache or military attache. in particular uniformed officers as attache

Answer 1

Which country do you mean by "we"?

Generally, the Ministry of Foreign Affairs/Foreign Ministry/Department of State provides the way in for officials of other agencies/departments to join the ranks of a foreign mission.  Uniforms are generally only worn by military personnel, as warranted - suits are more typically worn.