nrf_twi_mngr_transfer_t and const write data

[ms360]

I am trying to populate a nrf_twi_mngr_transfer_t at runtime depending on chunks of an input file that I'm pushing to i2c. 

nrf_twi_mngr_transfer_t const write_cfg_transfers[] = {

   NRF_TWI_MNGR_WRITE(bytes[0] >> 1, &data, i-1, 0),

};

Then I get a build error - 

error: initializer element is not constant

How is this done? 

I've tried using the twi instance from the twi_mngr struct, I can see it on the wire, but I get a hardfault on invoking the callback (likley undefined at this point)

ret_code_t err_code = nrf_drv_twi_tx(&(m_nrf_twi_mngr.twi), bytes[0] >> 1, data, i-1, false);

[ms360]

For more context - I've inherited production code that is using TWI MNGR everywhere. 
It would take weeks to rewrite this using one of the other API's. 

Is there a magic combination of SDK_CONFIG options to use the TWIM driver with twi_mngr and nrf_drv_twi ?
It looks like if I can manage to define TWIM_PRESENT, the const qualifier should be dropped. 

//If TWIM is present buffers can only be in RAM

/*lint -save -e491*/

/**

* @brief Macro checking if buffers should be stored in RAM.

*/

#ifndef NRF_TWI_MNGR_BUFFERS_IN_RAM

#define NRF_TWI_MNGR_BUFFERS_IN_RAM defined(TWIM_PRESENT)

#endif

/**

* @brief Modifier used in array declaration for TWI Manager.

*

* @note For TWI peripheral array can be const, for TWIM array has to be located in RAM.

*/

#if NRF_TWI_MNGR_BUFFERS_IN_RAM

#define NRF_TWI_MNGR_BUFFER_LOC_IND

#else

#define NRF_TWI_MNGR_BUFFER_LOC_IND const

#endif