Is it possible for a Telegram Bot to whisper messages to one or more persons in a group chat? For example if I use a bot command in the group chat it would be nice that my command and the respond of the bot would only be visible for me and invisible for all other group members.
You can not make your own command invisible to other users, but you can make the bot answer to your command directly inside your private chat with bot. Also if it is really necessary, you can make the bot delete your message as soon as it sends the response to you privately. for deleting you can use a code like below:
await Bot.DeleteMessageAsync(ChatID_OF_Your_Group,Message_ID);
But my suggestion is to use Inline Queries. You can find more information about them here.
You can use inline queries to send commands to the bot in groups and super groups and to answer the inline queries directly, you can use a code like below:
await Bot.SendTextMessageAsync(update.InlineQuery.From.Id, "Your_Text");
Inline query commands will not appear in the group but their result will. And as you program the bot to answer the sender of the inline query directly, the response will not show up inside your group/supergroup. So, as you said they will be hidden. You can use a code like below:
if(update.InlineQuery.Query == "query_text")
{
await Bot.SendTextMessageAsync(update.InlineQuery.From.Id, "Your_Text");
}
I hope it will fix your issue.