IMO, it is best to mention everything since any gap/discrepancy will raise unnecessary doubts. You dont want it to delay your processing.
About exp letter for ALL the previous employers - good to have. But if you cannot get ALL of them, give an explanation about it. You can probably initiate a request to ALL your ex employers. Finally, for the ones who do not respond, you can show that you at least attempted. Employers are not in obligation to cooperate and CHC understands this.
About exp letter for ALL the previous employers - good to have. But if you cannot get ALL of them, give an explanation about it. You can probably initiate a request to ALL your ex employers. Finally, for the ones who do not respond, you can show that you at least attempted. Employers are not in obligation to cooperate and CHC understands this.