Consider the following, if you want to merge two veNFTs, therefore, you will get a combined C veNFT sum of A and B for the B's NFT locked time.
1) You should be able to see your NFT's id, which you want to merge, in the "Locker" subcategory.
2) Click "Manage" on the left side of your veiZi NFT, which has a shorter lock-up time. Also, keep in mind another NFT's id(in the following example is 345 ). If the 349 NFT staked kindly UNSTAKE NFT for the following process.
3) Find a search placeholder at the bottom of the page, input B's NFT id, click search, and the "Merge to" button.
4)Click "Confirm" and you will successfully merge into one veiZi DAO NFT