SQL> create table t(n int, c1 int, c2 int, c3 int)
  2    partition by range(n)
  3    (
  4    partition p_max values less than(maxvalue)
  5    )
  6  /

Table created.

SQL> 
SQL> create index t_c1_i on t(c1) local;

Index created.

SQL> create index t_c2_i on t(c2) local;

Index created.

SQL> create index t_c3_i on t(c3) local;

Index created.

SQL> 
SQL> select index_name, partition_name, high_value, status
  2    from user_ind_partitions
  3   where index_name like 'T_C__I'
  4   order by index_name, partition_position;

INDEX_NAME PARTITION_NAME	HIGH_VALUE STATUS
---------- -------------------- ---------- ------------------------
T_C1_I	   P_MAX		MAXVALUE   USABLE
T_C2_I	   P_MAX		MAXVALUE   USABLE
T_C3_I	   P_MAX		MAXVALUE   USABLE

SQL> 
SQL> alter table t
  2    split partition p_max into
  3    (
  4    partition p1 values less than(25),
  5    partition p2 values less than(50),
  6    partition p_max
  7    )
  8    update indexes
  9    (
 10  	 t_c1_i
 11  	 (
 12  	   partition p1,
 13  	   partition p2,
 14  	   partition p_max
 15  	 ),
 16  	 t_c2_i
 17  	 (
 18  	   partition p1,
 19  	   partition p2,
 20  	   partition p_max
 21  	 )
 22    );

Table altered.

SQL> 
SQL> select index_name, partition_name, high_value, status
  2    from user_ind_partitions
  3   where index_name like 'T_C__I'
  4   order by index_name, partition_position;

INDEX_NAME PARTITION_NAME	HIGH_VALUE STATUS
---------- -------------------- ---------- ------------------------
T_C1_I	   P1			25	   USABLE
T_C1_I	   P2			50	   USABLE
T_C1_I	   P_MAX		MAXVALUE   USABLE
T_C2_I	   P1			25	   USABLE
T_C2_I	   P2			50	   USABLE
T_C2_I	   P_MAX		MAXVALUE   USABLE
T_C3_I	   P1			25	   USABLE
T_C3_I	   P2			50	   USABLE
T_C3_I	   SYS_P23128		MAXVALUE   USABLE

9 rows selected.