Convert single node to Clustered Nodes

I have a single node Elasticsearch instance. It had default Elasticsearch yml configuration as below. It has one index with some data.

# ======================== Elasticsearch Configuration =========================
#
# NOTE: Elasticsearch comes with reasonable defaults for most settings.
#       Before you set out to tweak and tune the configuration, make sure you
#       understand what are you trying to accomplish and the consequences.
#
# The primary way of configuring a node is via this file. This template lists
# the most important settings you may want to configure for a production cluster.
#
# Please consult the documentation for further information on configuration options:
# https://www.elastic.co/guide/en/elasticsearch/reference/index.html
#
# ---------------------------------- Cluster -----------------------------------
#
# Use a descriptive name for your cluster:
#
#cluster.name: my-application
#
# ------------------------------------ Node ------------------------------------
#
# Use a descriptive name for the node:
#
#node.name: node-1
#
# Add custom attributes to the node:
#
#node.attr.rack: r1
#
# ----------------------------------- Paths ------------------------------------
#
# Path to directory where to store the data (separate multiple locations by comma):
#
path.data: /var/lib/elasticsearch
#
# Path to log files:
#
path.logs: /var/opt/logs/elasticsearch/

#
# ----------------------------------- Memory -----------------------------------
#
# Lock the memory on startup:
#
#bootstrap.memory_lock: true
#
# Make sure that the heap size is set to about half the memory available
# on the system and that the owner of the process is allowed to use this
# limit.
#
# Elasticsearch performs poorly when the system is swapping the memory.
#
# ---------------------------------- Network -----------------------------------
#
# Set the bind address to a specific IP (IPv4 or IPv6):
#
#network.host: 192.168.0.1
#
# Set a custom port for HTTP:
#
#http.port: 9200
#
# For more information, consult the network module documentation.
#
# --------------------------------- Discovery ----------------------------------
#
# Pass an initial list of hosts to perform discovery when this node is started:
# The default list of hosts is ["127.0.0.1", "[::1]"]
#
#discovery.seed_hosts: ["host1", "host2"]
#
# Bootstrap the cluster using an initial set of master-eligible nodes:
#
#cluster.initial_master_nodes: ["node-1", "node-2"]
#
# For more information, consult the discovery and cluster formation module documentation.
#
# ---------------------------------- Gateway -----------------------------------
#
# Block initial recovery after a full cluster restart until N nodes are started:
#
#gateway.recover_after_nodes: 3
#
# For more information, consult the gateway module documentation.
#
# ---------------------------------- Various -----------------------------------
#
# Require explicit names when deleting indices:
#
#action.destructive_requires_name: true

Now I want to convert this to cluster with 2 new nodes. Can I achive this without wiping data from first node? I dont want customer to do snapshot & restore for converting this to cluster. Im using ELK 7.10.2

Does Add and remove nodes in your cluster | Elasticsearch Guide [7.15] | Elastic help?

Please upgrade, that release is a year old now and 7.15 is latest.

We need to plan for upgrade. In 7.10.2, how to handle this situation

Sorry if Im not clear. I already tried above link. I followed below

  1. Three nodes were running individually as default clustered nodes
  2. First node yml file updated. Data directory was not deleted here as I need the data inside this node. At this time other two nodes were running as single nodes cluster
  3. Second node yml will be updated. Deleted data directory. Started second node.
    Third node still running in default mode
  4. Third node yml updated. Deleted data directory. Started third node.

I asked similar question earlier in a different context Elasticsearch 3 nodes cluster not joining with each other - #16 by RAM_NATHAN

I got an answer that to avoid multiple clusters, we need to wipe the date in all three nodes , do a snapshot and restore.

Now my question is in 7.10.2, can I create a cluster without deleting my first node data?

The answer is still the same sorry to say.